50 years of Celsius weather forecasts – time to kill off Fahrenheit for good?

Fifty years ago, on 15th October 1962, British weather forecasts switched over from the Fahrenheit scale to Celsius. Fifty years on, some parts of the British media inexplicably cling on to Fahrenheit measures, and the UK Metric Association (UKMA) says it’s time to kill off Fahrenheit for good.

[Press release issued on 15 October 2012]

The UK Met Office has used the Celsius scale – formerly known as “centigrade” – in its work since 1st January 1961, to allow for greater international co-operation and because of the convenience of the scale. As the Met Office reported in 1962, this “led to the consideration of the desirability of introducing it in weather reports and forecasts for the general public.”

With the agreement of industry and the government, the Celsius scale was given after Fahrenheit from January 1962 as an interim measure, and then from the 15th October, Celsius became the primary unit given, with Fahrenheit retained as a secondary unit to aid the transition “for a period of several years.”

The Met Office is to be commended for accomplishing the change to the metric system of measurement so rapidly, in sharp contrast to some other parts of the government, such as the Department for Transport, which is still, fifty years later, dithering even about adding metres to safety-critical warning signs.

However, despite this early and rapid switch to Celsius-first forecasting, at the time of switchover, there was no timetable for the withdrawal of the Fahrenheit secondary measure. Says UKMA Chairman Robin Paice, “The officials at the Met Office in 1962 would almost certainly be incredulous at the prospect that, fifty years later, some media outlets would still be using Fahrenheit, and in some quarters, even as the primary scale. Two generations have now passed since Celsius was introduced, and yet we still see occasional headlines, normally in hot weather, about the temperature given in Fahrenheit.”

UKMA believes that with fifty years of Celsius weather forecasting now behind us, it is time for the British media to ditch Fahrenheit for good. “Media outlets should reflect on how they reported decimalisation; “new pence” are almost a decade younger than the Celsius temperature scale, and yet no newspapers feel the need to convert pence to shillings in their reports, and rightly so; why cling on to an even more obsolete temperature scale?”

The Met Office declined an invitation to comment.

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175 Responses to 50 years of Celsius weather forecasts – time to kill off Fahrenheit for good?

  1. BrianAC says:

    Here are a couple of nice precise measurements taken from an American astronomical telescope article, ' ... no part of the glass surface must depart more than 1/4 wave or 51/2 millionths of an inch from the specified shape. ' ... and 'this becomes 445/28 = 16X. Notice that this is in millimeters. It can also be done in inches, as: 17.5/1.1 = 16X. ... '.
    I have to say this was the first time I had ever seen the wavelength of light in inches, I just had to keep the article. You can't get much more precice than elswhere in the article ' ... = 0.000027" (2 3/4 millionths) ... ' that we will all recognise instantly as the 1/8 wavelength of green light.

  2. RT says:

    @John Steel
    "Are you suggesting British are dumber"
    Please check death by road accident DATA. UK is #180 of about 189 nations - among the lowest in the world. Caring more for "PEOPLE's life" - is a good BRITISH virtue & imperial road signs paid off.
    "We live in digital world"
    Digital means - binary NOT decimal. The Imperial System is binary 1/2, 1/4, 1/8, 1/16 etc. The decimal metric system is NOT and requires a "floating point co-processor or software" to round up & down - introducing the inaccuracies most people do not realise.
    Vast quantity of past experimental research DATA were done, recorded and published in US customary units.
    Demanding "one METRIC system" now is NOT realistic nor practical. People who never send anyone to the moon, telling Americans to come down to their lower level?
    Learning how to convert is the way. In the digital age, google, computers, smartphones etc are invented by a free country using non-metric units. Freedom is the reason of success and to maintain freedom, metrication has to be voluntary.

    NASA was successful for 50 years before Metricaton cause disasters. The official

  3. derekp says:

    "Imperial is binary".
    We surely can't be thinking of the same Imperial:
    12 inches to a foot, 3 feet to a yard, 22 x 10 x 8 yards to a mile;
    12 troy ounces to a troy pound;
    16 avoirdupois ounces to an avoidupois pound but 14 pounds to a stone,
    and 2 x 4 x 20 stones to a ton;
    22 x 22 x 10 square yards to an acre;
    20 fluid ounces to an Imperial pint.
    But, I agree there are 8 pints to a gallon, US or Imperial.
    Perhaps you were just thinking about the pub (and who can blame you?)

  4. BrianAC says:

    Yes. ... and the gallon is the only unit we really do no longer use in the UK! No connection of course.
    Talking of pubs, does anyone really know what a unit of alcohol is? I have no idea myself so another slug of wine I think.

  5. Michael Glass says:

    According to Wikipedia, http://en.wikipedia.org/wiki/List_of_countries_by_traffic-related_death_rate deaths by road accidents in the UK are very low (3.59 per 100,000), but the death rate is lower in Sweden (2.9/100,000). Canada (9.2/100,000) and Australia (5.71/100,000) have a lower death rate for road accidents than the United States (12.3/100,000). So when you look at the figures there isn't any evidence that imperial measurements keep road users safer.

    Australia changed its road signs in July 1974 and this happened without incident. Therefore the idea that changing the road signs would cause chaos is simply not sustainable.

  6. John Steele says:

    Wikipedia has an article on traffic fatalities measured by three metrics The obvious one is deaths per billion vehicle -kilometers, as the other two depend heavily on the percent of car ownship. The UK has an excellent record at 5.7. However, Australia is very comparable at 5.8 and is metric. Sweden and Switzerland, both metric, are superior at at 5.1 and 5.6.

    The US is 8.5 and we have 99+% Customary signs although metric signs are legal (but the States mostly won't agree to use them). Canada, which is metric, stands at 8.2, better than the US. Do you suppose there could be other factors besides Imperial/metric.

    Two that obviously have a huge effect between US States (and I assume internationally) are seat belt law compliance, and drunk driving.

    Yes, computers use binary, but their masters use decimal and they emulate well, to 15+ decimal digits with double precision floating point which has become the norm as memory gets cheap. Many calculators perform BCD math so they are truly decimal. Perhaps the US is more decimal than the UK. Our currency has "always" been decimal, we quit using chains and have surveyed to the 0.01 foot for decades, nearer a hundred years actually. Let me be blunt, fractions are for carpenters, a machinist wouldn't use them. Non-metric machining is normally to 0.001", precision machining to 0.0001"

    I will point out that NASA got TO Mars on metric, then augered in due to orbit manuevering thrusters working in Customary, due to a software error (and contractual non-compliance) by a supplier. NASA has a fairly poor record on metric because they are always trying to reuse 40 year old hardware designs, but they are working towards being metric. NASA also converts for public consumption; however, as far as I can tell, the current Mars rovers are metric.

  7. John Steele says:


    The UK "unit" of alcohol is 10 mL (1 cL) of neat ethanol. The US uses a unit of 0.5 US fl oz (about 15 mL). It is not clear to me why the UK goes out of its way to avoid publishing a rigorous definition of the unit, and showing pictures of wine (or beer) glasses with %ABV and number of units worked.

  8. Jake says:


    I'm not sure what your background is, but if you really think that google, computers and smartphones are designed and produced in non-metric units (I am assuming you mean US Customary), then you are are seriously mistaken. The discussion here is not about freedom or supremacy, it is about modern units of measurement; on this thread: ditching the remaining vestiges of the Fahrenheit scale in the UK half a century after we dropped it officially. You seem to have the USA as your champion, and there's nothing wrong with that, but if you think that the USA survives in the modern world without metric units then you should do some research before making your claims.

  9. Arian Ward says:

    Oscar Garcia - I agree with many of your points about Celsius vs. Fahrenheit but definitely not with the following part of your response.

    My main point of disagreement is that I was talking purely about my personal preferences, experiences, and abilities, purposely trying to avoid making general statements. So I don't believe that you can accurately tell me what I prefer, experience, or am capable of doing or feeling. No one can do that for any other person. I learned that a long time ago in psychotherapy. As I explicitly stated, "The one aspect of the Celsius scale of temp measurement that I don’t like (as used in non-scientific settings), and prefer Fahrenheit..." [notice I said "I don't like ... and prefer...", only referring to myself, no other contexts. I also explicitly excepted scientific settings, where I agree 100% with you that Celsius (and when needed, Kelvin, because it uses the same scale, just different zero points) should be the only temp measurement system used worldwide. So I was referring only to myself in the context of my everyday personal life - an area only I am an authority on, just like you are the only authority on your own personal life. And I definitely wasn't arguing for not going metric - I think we should have done that decades ago. In fact, during the push for metrication during the Carter administration, my brother headed up the Minnesota Metric Center (or some such name). [Is the right term for this metrication or metrification?]

    And yes, I absolutely can detect a 1 degree F change in temperature. Many people have witnessed it as I tell them the temp and then they check it with a thermometer. But I agree that it's unusual, but that describes my life and my abilities. I couldn't do that 15 years ago, when I was living in LA. Since then, I've lived on a mountaintop in the giant redwood forests along the California Central Coast - pure air, pure water, quiet, secluded, surrounded by wilderness, totally natural setting, spending more time with animals than with humans because I run a small animal rescue here, spending about as much time outdoors as indoors. That means my sensitivities, abilities, preferences, experiences have returned to the more natural tribal state where people not only could detect temperature but just about every other atmospheric state that modern weather instruments measure - wind velocity and direction, changes in barometric pressure, the smell and feel of different approaching systems - rain, heat wave, thunderstorm, hailstorm, snow, sunny pleasant weather, etc.

    So that's where I'm coming from - just from personal experience and preference, nothing more.

    - Regarding Precision: I agree that the number of significant digits in a measurement does not fit the scientific definition of precision which in a nutshell means reproducibility - the degree to which a series of measurements cluster around one value. But "degree of precision" IS a term that is used in common, non-scientific use to mean number of significant digits displayed like in this Yahoo question (http://answers.yahoo.com/question/index?qid=20101020211912AA9kwNf) :
    "What degree of precision (how many significant figures) can you obtain..."

    But I agree in this forum I should have been more diligent in my choice of terms because this seems to be a more scientific context. My reversion back to sloppy common speak vs. the way I used to talk when I was studying and working in more scientific disciplines tells me that I'm already getting intellectually lazy since I recently retired. LOL

    Peace! Arian

  10. RT says:

    Hey this is what I mean. In the imperial system you can always divide any unit by 2 because it also includes a "fractional" system.
    1 yard divided by 2 = 1/2 yard = 1-1/2' = 18"
    1/2 yard divided by 2 = 1/4 yard = 3/4' = 9"
    1/4yard divided by 2 = 1/8 yard = 3/8' = 4-1/2"
    1 mile divided by 2 = 1/2 mile = 880'
    1 troy pound divided by 2 = 1/2 troy pound = 6 troy ounce
    etc etc.
    reciprocal of 1,2,4,8,16,32,64,128 is what I mean by binary.
    You cannot do that in the decimal metric system and rounding is always required.
    25mm (about 1") divided by 2 = 12.5mm
    12.5mm divided by 2 = 6.25mm
    6.25mm divided by 2 = 3.125mm
    When you buy a pizza/cake you always cut into 2 or 4 or 8 in a binary way. Never 5 or 10.
    When you buy 1lb of meat you can feed 4 in the family each having a quarter-pounder = 4oz each.

  11. philh says:

    1 metre divided by 2 = 500 mm
    1 metre divided by 4 = 250 mm
    1 metre divided by 8 = 125 mm

    1 kg divided by 2 = 500 g
    1 kg divided by 4 = 250 g
    1 kg divided by 8 = 125 g

    Fractions of the form 1/2^n can all be expressed exactly in decimal
    q.v. 1/2 = 0.5, 1/4 = 0.25, 1/8 = 0.125, 1/16 = 0.0625 ... and so on.

    Imperial rulers are seldom marked in divisions smaller than 1/16 of an inch. Nearly all metric rulers are marked in mm.

    1 mm is smaller than 1/16th of an inch.

    So which gives us more accurate readings?

  12. John Frewen-Lord says:

    Oh my, this discussion has gone a long way, and far from its original premise. To all those (especially RT) arguing that imperial (or its equivalent, USC) is superior, for whatever reasons, it DOESN'T MATTER! Metric measurements are used by 95% of the world's population, whether in scientific circles or in everyday usage. The large emerging economies - Brazil, China, India, Russia, etc - are all metric. Why would they choose metric? After all, they have a choice. Especially Brazil, which was so heavily influenced by the USA and Britain for so many years (up to the mid-twentieth century, Britain owned nearly the whole of Brazil's railways, along with huge tracts of land, all its banks, etc).

    These countries chose metric because (a) it is better, and (b) it is what the rest of the world is using. Just look at Michael Palin's series on the BBC on Brazil. Any clips showing everyday Brazilians talking about an aspect of Brazilian life will always involve metric measures, never imperial.

    RT, you have the choice of course of using whatever measurement units suit you, but to fight against metric usage is to swim against the tide, with no advantage at the end. Why bother? Metric is here to stay, and you (and even the whole of the USA) will not persuade 95% of the world's population otherwise. Eventually the USA will see sense and become officially metric. That will be the time the world will see a USA renaissance.

  13. Ken Cooper says:


    With regard to distances, I note that you started your "fractional" theory with the yard and worked downwards, then suddenly jumped up to the mile and started working downwards again.

    Why did you miss out the intervening imperial distance measures?

    I can get from the mile to the furlong using your fractional method. Can you explain how to get from the furlong to the rod (aka pole or perch) and from there to the yard?

    Incidentally, previous pro-imperial visitors have suggested that the foot is the basis of the imperial length measurement system. I note that it appears to be missing from your explanation. Can you explain why?

  14. John Steele says:

    Apparently, Imperial is so confusing as to confuse its proponents. I would note that 1/2 mile is 2640 ft, not 880 ft (I think that is the number of yards in a half mile). I would note that 5280 is not particularly binary, having factors of 32*3*5*11. I am not sure if Ken's question is inquiring about the 10 chains per furlong, or the 11 yards in a half-chain, but they aren't very binary.

    I would note as we subdivide the avoirdupois pound, ultimately there are 7000 grains, and in the troy pound, 5760 grains. As we address multiples of the pound, we trip over the 14 pound stone to the 112 pound hundredweight, and 2240 pound long ton (Americans use 100 lb hundredweights and 2000 lb short tons), again, not very binary.

    The American gallon (128 fl oz) is more binary than the Imperial gallon (160 fl oz) until you realize the American gallon is 231 cubic inches (factors of 3*7*11) and has no binary whatsoever. (Our fluid ounce is a convenient 231/128 of a cubic inch). The Imperial gallon is 10 lb of water; where's the binary in that?

    The binary (and duodecimal) arguments are largely cherry picked examples which quickly fall apart when you examine the total maze-like complexity of either Imperial or Customary, It would be well worth packing them both off to retirement as obscure literary references and be able to understand and be understood by the rest of the world.

  15. philh says:

    Opponents of UK metrication argue that it should be voluntary (as did RT above). History shows that the purely voluntary approach never works.
    So insisting on it being voluntary is the same as saying we mustn't do it at all.
    So what are we left with?
    Two incompatible sets of units applied sporadically to different applications in various circumstances.
    OK so we have freedom to choose ... or do we?
    I choose to weigh myself in kg and don't want to know about stones and pounds. When I go to weight watchers meetings I am forced to weigh in imperial as well as metric. I get awards for key stages in pounds only.
    So where is my freedom to choose? There is no law requiring organizations like Weight Watchers to work in either units so the pressure is there purely as a result of the UK measurement muddle.
    Freedom to choose is an illusion and those who argue on libertarian grounds are being disingenuous.

  16. BrianAC says:

    I am getting lost on this thread. I know more about the Imperial system, even more the USC, now than I have ever know in my last 68 years. I don't feel any better for knowing that. I think it an even more stupid system than ever.
    It was, and has always been, a load of odd-ball measurements used by various traders, farmers and businesses cobbled together at some stage to make a so called system. Little or nothing was ever inter-related. 1 gall=10 lbs was totally accidental. Beyond each individual application it was never really ever fit for purpose; neither can it ever be made so.
    The only real puzzle that has confused me ever since I asked my dad what the figures on the radio dial meant (including metres) way back long before I was a teenager, is WHY? Why does any sane, knowledgeable person want to hang on to this stupid system? Nothing put forward so far makes any sense and is without reason nor common sense. Answer me that and I have found the meaning of life itself. (Or maybe the reason for getting out of it).

  17. BrianAC says:

    Oh, and before someone suggests it, I have read almost all of the blurb, including the newsletters, on "the other site" that I won't even name, and have found little or nothing that makes any real sense.

  18. Ken Cooper says:

    @John Steele

    I was meaning going from mile to furlong in 3 binary steps i.e. Mile>>1/2 mile>>1/4 mile>>Furlong

    I purposely referred to the rod as it is the most crazy definition in the whole "system". Where else but Imperial can you find something as incomprehensible as 5.5 yards = 1 rod?

    Totally agree with your last paragraph, by the way.

  19. John Steele says:


    I don't think the rod was used much in the US. However, in the 1800's, the chain (4 rods) was used a lot for surveying, basically the entire Midwest under the Public Lands Surveying System. No fractions for us, it was decimal. Chains had 100 links, 7.92 inches long, and results were written as chains and links or decimal chains. Later surveyors changed to decimal feet, no inches, which is still used except where they have gone metric.

    As an example of too much choice, most State Plane Coordinate Systems are based on the foot, but the Military Grid Reference System and the US National grid are based on the UTM projection in meters. Never the twain shall meet. Our topographic maps are a clutter of different grids, lat/long, SPCS to old and new datums, USNG. You can hardly see the ground for the grids. A prime example of choice going completely bonkers. On some computized ones, you can turn off grid layers you don't want.

    Choice means understanding two systems poorly instead of one system well, unles you waste a LOT of time understanding two systems.

    I fully agree with the comments that none of it makes sense, but the more you document it, the more nonsense it makes.

  20. michduncg says:

    @PhilH - try Jenny Craig weight loss. Former Spice Girl Mel B advertises for them on TV and explains her weight loss target was 5kg in their info-mercial.

  21. BrianAC says:

    @ michduncg
    A quick browse of that site and it is all in lbs I am afraid. As many say, loosing weight is in lbs, gaining it (body building) is in kg. That site even asks for your weight and height in stones and feet to work out the BMI.
    So much for the TV ad. Good work by Mel B though.

  22. michduncg says:

    Well, the BBC continues to prove hopelessly inconsistent in its approach to metric measurements. While at the at gym tonight, plodding away on my 5.5 km run in an effort to shed some grammes, I saw that the BBC 'One Show' was having some feature on that involved a police style line-up of people having their height measured. I could clearly see that the left hand side of the height chart behind these folk was marked in feet. I kept waiting for a camera shot on the right hand side to see if they had metric markings on the other side. Unfortunately, it didn't. It was also marked in feet. So, here we are, with a popular programme hosted by young presenters (they are both under 40) perpetuating the usage feet and inches. And they wonder why todays kids are so bad at maths and science.

  23. BrianAC says:

    The One Show is one of the worst on BBC for not using metric, closely followed by Country File. All the more dissapointing as it is very much a family show and frequently involves young children who are then totally exposed to and reverse educated into a useless system which is technically no longer used in UK.
    Opposite to what others here percive, in my view it is getting widely and rapidly worse now the Olympic memory is fading. Tonight we have snow back, in inches of course, in both local and national forecasts.

  24. BrianAC says:

    It seems the weather forcast confused the local rail companies too. The afore mentioned snow took them by surprise. And yes, that was the excuse, they got their forecast wrong!
    So Celsius or Farenheit, mm, inches or feet it seems the railways, among others will never get the message.

  25. John Gow says:

    All you people that say we 'have' to use metric are acting like controlling fascists! what is your hatred of the imperial system? @BrainAC I have a 5 year old son who is just starting school. i have excplicity taught him in stone lbs and oz's, °F, miles yards etc. It is part of our heritage and incidentally °C is not a metric nor SI unit. °F are is a far better and more logical scale for climate along with lbs and oz's for cooking, amongst most other imperial units.

  26. John Frewen-Lord says:

    @John Gow

    Oh gosh, here we go again, another person stuck in the 19th century, oblivious as to how today's world really is, and instead intent on hobbling this country's future generations.

    "I have a 5 year old son who is just starting school. i have excplicity taught him in stone lbs and oz’s, °F, miles yards etc. ". I hope you feel proud that you have crippled your son in his ability to converse with the rest of the world for the rest of his life. I am glad that my son, an engineer, is free from such nonsense, and can (and DOES) communicate freely and seemlessly with his counterparts around the world (including American automotive engineers who are also metric).

    "It is part of our heritage" No it is not. Fahrenheit was GERMAN, the libre (abbr. lb) was ITALIAN. Other units can be traced back to other cultures. If you want a measuring system that is part of our heritage, then go metric - John Wilkins in the 1600s is credited with the first decimal based measuring unit, while there is evidence of English decimal measuring sticks almost exactly 1 m long (997 mm to be precise) dating from the Middle Ages. Lord Kelvin created the current SI temperature scale, from which the Celsius scale is an offset, but with the same increments.

    "°C is not a metric nor SI unit" Not SI, but it is a metric unit - see previous paragraph.

    "°F are is a far better and more logical scale for climate" Nothing is more logical than 0 degrees for freezing water and 100 degrees for boiling water. °F is utterly illogical.

    Not being totally metric, and having to deal with two measuring systems (imperial of course is not really a system) costs this country tens (maybe even hundreds) of millions of pounds a year. YOU Mr Gow are helping to perpretrate this drag on the British economy. And that is nothing to feel proud about. As for calling metric supporters fascists, those demanding the continuation of imperial units are invariably the most fascist of all. The fact is, ALL countries have some form of SINGLE weights and measurement legislation, to protect consumers, provide standards, and facilitate trade. Nothing fascist about that.

    Finally, if you think the imperial system is so superior, then take a look at this earlier post in Metric Views at


    and then tell me that it is still superior.

  27. BrianAC says:

    My personal hatred of the Imperial system is its total impractability in most aspects of life. I was about 7 (over 60 years ago) when I found out there was a much better system in world wide use, that is what I try to use. Celsius is an SI unit, it is used because it is a domestic unit compatible with Kelvin. Kelvin is not an SI unit, but is the only unit than can be used for calcuations at all temperatures and probably the one most often used and impacts on every aspect of everyday life.

    I guess your son will be able to communicate with a few like minded people, such as his parents, but Imperial will be, and for the most part already is, totally useless in the work place. This is one of the reasons UK people can't get jobs in UK and employers prefer other Europeans. It is another reason why Germany is doing well and we have lost almost all of our former industry and are faced with another decade of austerity. Any calculation on any subject requiers units to be the same. Feet and inches has first to be changed either to feet or inches, stones, pounds and ounces would need first to be reduced to just one unit. Try working out your sons BMI for instance in feet, inches, stones and pounds, then do it in kg and metres. We HAVE to use metric to communicate with and compete with, the rest of the world, that includes America whos international trade is also metric.

  28. Jake says:

    @John Gow

    25 years ago my wife and I taught our children French and German, both of which they could understand at the age of 5 (in addition to English). That has proved to be much more useful to them in their lives than teaching them imperial units could ever have been. In the fullness of time you son will be able to make up his own mind whether imperial units are actually a part of our heritage to be cherished or in actual fact a millstone round the country's neck.

  29. michduncg says:

    @ John Gow - I really think that it is time people got over this and moved on. A legitimate UK Government made the decision on behalf of the UK to go metric in 1965. We have had nearly 50 years to get used to it and get on with it. All metric supporters want is whats best for our country, as did the CBI who recommended the move all those years ago. Pretty much every other major country in the world has managed to go metric, including all of the Commonwealth countries. As others have said, Imperial is less British than the metric system. There is really no basis for clinging on to this relic.

    I wonder what career expectations are for your child? As a retail manager I can tell you that if you are educating your child in Imperial they won't even be trained to be a shelf stacker in a supermarket! All our shelf layouts are arranged in millimetres, our temperature checks are all carried out in degC, the food we sell is packed in metric measures. Our fruit and veg departments all use metric scales, as do our food service counters where all food has to be served in grammes.

    Of course, if you have higher aspirations for them then you would be better off teaching them a foreign language - and metric. Its the international language of measurement.

  30. gary sear says:

    John Gow what a selfish man you are, trying to sabotage your own son's education because of your own beliefs. They have been teaching metric in our own schools for 40 years, so why dont you try and embrace it? It is what your son is taught school, so why dont you do yourself a favour and sit down with your son and learn with him. Are you going to teach your son to fill his car in gallons as well?

  31. gary sear says:

    it is what your son is taught in school, was what i meant to say.

  32. philh says:

    John Gow said: " ... incidentally °C is not a metric nor SI unit."

    May I refer Mr Gow to the SI brochure:


    In particular I draw attention to section 2.2.2 Table 3 "Coherent derived units *in the SI* with special names and symbols" (my emphasis)

    In that table Celsius is listed with the special symbol °C as being derived from kelvin. There is also a footnote which says:
    "The degree Celsius is the special name for the kelvin used to express Celsius temperatures. ..."

    So it clearly is part of the SI. As for it being metric, well that depends on what is meant by the term but here we generally regard the metric system and the SI as one and the same. At any rate the SI is currently the only officially recognized system that incorporates metric units as we understand them.

  33. timward says:

    "weather forecasts" celcius, centigrade, fahrenheit or even Kelvin. No one has mentioned what happened to wind speed. This should be in Knots as layed out in the Beufort scale. Even when we have inflight information the air speed is in MPH what is wrong with knots. Shipping forecast refers to wind speed in Force 8 etc.

  34. BrianAC says:

    “Weather forecasts” Celsius, centigrade, Fahrenheit or even Kelvin. No one has mentioned what happened to wind speed.
    Oh yes, wind speed in Knots? I think m/s would be more useful to most of us. You left out the pressure too, and cloud cover in octas or whatever. We tend not to hear too much from pilots about weather. They are very truly stuck in the past with the flight level in feet and ranges in miles. I even saw an altimeter recently that was set to inches for barometric pressure, my word that took me back a bit! Took a while to work out what it was. I don't think there is much Mr. Joe Public Bloggs can do about that. Pilots get their weather from the airport control on approach to landing; they have their own language that few others understand. But I agree that air traffic control should use SI, and only SI. Only Russia and China use metres for altitude. Not exactly a small segment of the world’s airspace.
    I thought on the BBC national weather last night, no pressure map, how much more information that would add to the forecast. Fortunately our local map always has those isobars to show the real weather pattern.

  35. Michael Glass says:

    I find reports of wind speeds really frustrating. In Australia, it appears that wind speeds over land are reported in km/h while wind over the sea is reported in knots. I find it a real bugbear. I wish they would use just one measure.

  36. philh says:

    No one had mentioned wind speed prior to timward's comment because it is not the subject under discussion. The point of the article is that Fahrenheit is obsololete in the UK and has been for 50 years. There is really no excuse for anything other than Celsius.

    km/h for windspeed is yet to be introduced in UK forecasting and is probably being held back by the official retention of the mile and mph on roads.

    Knots and the beaufort scale are a maritime convention still used internationally, but not suitable for domestic forecasts.

  37. John Steele says:

    The US and Canada both use knots for all their marine and aviation weather products, and do not use the Beaufort scale. However Canada uses km/h for "civilian" forecasts, while the US uses MPH. The Wikipedia article implies only a few nations still use the Beaufort scale.

    (However, the wind speeds for small craft warnings, gale warnings, storm warnings and hurricane warnings bear an obvious relationship to Beaufort forces, but expressed in the above units.)

  38. tim ward says:

    It just goes to show how confusing our measurment system has become.

    We are stuck in our ways? Nothing gets updated quickly they tend to fade?
    We still say, Touch wood. surely this should now be, Touch plastic? or anything else modern.
    Back to the drawing board. We now use CAD. "back to the cad"? perhaps not many people know what CAD is. but they do know what a drawing board is.

    In deed Isobars do tell you everything . For those who know about weather.
    But not everyone is educated to the same level. I was tought by my father (who was in the RAF as Observer Navigator) about the weather and charts etc. My mother had a thermometer to check the nappies were boiled properly. Yes it was in Fahrenheit, 212deg had a red line. The old medical thermometer for checking body temp. 98.4deg. Filled with mercury. mmm H&S?
    The back cover on all exercise books had The Times Tables, measurment and weights printed on them. Easy reference.

    One tends to remember what one was tought at an early age.

  39. tim ward says:

    The original point of discussion is:- Why do we still use old measurements (non metric) whatever they are? I can remember when athletics changed from imperial to metric back in the 60s. So why do we still, in football, refer to areas as, the 6yd box
    and 18yd box.
    Perhaps we are just traditionalists and like to preserve old ways of life.

  40. matt smitt says:

    Alot of people maybe Tim, but there alot of us who want to change, i never use yards in football, I use the word metres. Rugby league uses metric, hopefully football will go the same. And it is sad to preserve the old ways of life, when the future generations should be put first, and what are our children and grand children taught? Thats right-METRIC!!

  41. Jake says:

    Preserve old ways of life? Like ploughing with oxen instead of a tractor? Having coal-fired steam trains belching out acrid smoke? Riding in a horse and cart? Of course all these things are interesting to watch at shows and exhibitions but no one would seriously suggest reverting to the ways of life of the 1940s or before. It is the same with measurement units. Imperial units and their predecessors, just like early forms of currency, are fascinating to read about or see in a museum but they are not part of what Britain is trying to be, namely a modern, forward-looking country. There is only so much of the past you can preserve before the country fossilises into a theme park. It is time for politicians to grasp the nettle and tie together all those loose ends in the metrication process, especially ditching references to Fahrenheit (if someone doesn't understand Celsius, it is not unreasonable to expect them to learn it) and modernising our road system by showing speeds and distances in the metric units taught now in schools for around 40 years.

  42. Han Maenen says:

    Before winter came to The Netherlands about 10 days ago, it was mild and cloudy. At the same the temperature in Australia was 44 degrees Celsius. A weatherwoman told us that following the news. Then she showed us a thermometer with C and F and she told the listeners that the temperature in The Netherlands had been 44 degrees too, but she said that that was on the Fahrenheit scale.

  43. Dan Thompson says:

    Why do people connect the Celsius temperature measurement with the metric system? They are two completely independent systems. The Celsius scale was invented by Anders Celsius, a Swedish astronomer, in 1742 and independently by Jean-Pierre Christin, a French physicist, in 1743. The metric system was created in France around 50 years later. Celsius is not part of metric system.

  44. philh says:

    The modern metric system is the SI. That system has kelvin as the base unit for thermodynamic temperature. The kelvin scale has been derived from Celsius in terms of the temperature change represented by 1 degree - they are the same for both scales. Celius is accepted for use with SI and is the recommended non-scientific alternative to kelvin. At any rate it is highly compatible.
    The same cannot be said of fahrenheit which is totally incompatible and has no sensible origin for present day purposes.

  45. BrianAC says:

    During a bored moment today I picked up a copy of the Daily Mail. A big heading on page three said "89f today..." or some such, even a small "f". I then looked at the weather, all in dual C and F, so Fahrenheit is alive and well in the newspapers. I did not get far with the rest of the paper either. I did not realise that papers still used these units until they got to 100! Perhaps they can't wait that long.

  46. Michael says:

    Hmmm. Then that just shows how inconsistent the Daily Mail is. Only the other day I commented to a colleague that they had a headline about the hot weather stating '30°C weather on its way'.. This was only last week and the entire article referred to temperature in Celsius. I thought we had turned a corner for a moment! That said, at least BBC1 seems to have broken the habit of converting hot temperatures into °F.

  47. Han Maenen says:

    Ireland is in a hot spell at the moment, the first days of this week are moderate, but from coming Thursday the temperature will soar again to the upper twenties or maybe the lower thirties. I have not seen the re-appearance of Fahrenheit in the Irish media; in all news items about the heat I saw Celsius only. Even the Irish Daily Mail had no Fahrenheit; however this newspaper has really become an Irish one and is much more metric than its mother in the UK.
    I encountered an error in a computer shop in Belfast where laptops are sold stating the screen diameter in feet, not in inches. 15.6' instead of 15.6''. I did not expect to see this error in the UK. When I bought a flat screen for my computer some years ago it was stated as 24' and not 24'' (not by the manufacturer, who gave the two sizes, 24 inch and 60 cm). I would need a removal van to to take such a giant device home! It should have been 60 cm of course. These '24 inch' screens measure in fact 23.6 inches and that is exactly 60 cm. And how rational is a size like 15.6 inches?

  48. Wild Bill says:

    I listen to Christian O'Connell's Breakfast Show on Absolute Radio (Medium Wave) as I wake up in the mornings, and the question of Fahrenheit broke out there a couple of weeks back. Their weather man would occasionally drop a "and that's 85F" sort of comment in after doing all the rest of the temperature information in Celsius.

    A couple of weeks back, O'Connell's sidekick Richard decided to challenge the usefulness of such statements, which broke into the usual acrimonious verbal punch-up, and possibly led to listeners emailing or texting in their comments. I don't know what happened next, but I haven't heard a temperature given in Fahrenheit on the Breakfast Show since!

    ...Until today when a listener had contributed to the "who's got the worst job in a heatwave" thread that was running this morning. Her statement was that she worked in a kitchen (or whatever it was) and "the temperature had got to 115F the previous day". Now that did surprise me - where would anyone find a Fahrenheit thermometer these days? But whatever, it provoked the show's presenters to have to get out the pocket calculators and eventually announce "that's 46 degrees - wow, that's hot!"

    My personal experience is that even old ladies on the bus talk about the weather in celsius. The only place in Britain that I can reliably expect to see Fahrenheit is the front page of the Daily Express in the summer months. I don't know why they do that - I'm not sure where their Fahrenheit-loving readers are supposed to be. I've never met one.

    Mind you - I wouldn't want to.

  49. BrianAC says:

    In answer to Wild Bill "Now that did surprise me – where would anyone find a Fahrenheit thermometer these days?"
    The answer unfortunately, is just about everywhere, like tyre (tire) gauges with psi on them many if not most are still dual calibrated. Even the thermometers I bought in France are dual calibrated. Try to find a tyre gauge in kPa only in UK!!!
    The only thermemeter I have in C only is and old garden one probably dated to the mid to late '70s when items were often metric only. We have progressed backwards quite a lot since then.
    I hate dual calibration, it is so erksome that every day items such as thermometers and tyre gauges should present me with figures I really want to forget but will never be able to.
    I did replace my mechanical CH thermostat with an electronic centigrade one some time ago, but it is so bad that I am thinking of putting the old F one back.
    That is modern progress for you.

  50. Ezra Steinberg says:

    Forgive this macabre tone, but once those Daily Express editors and writers have retired or died, Fahrenheit will die there, too.


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