December CET Figure Released

[West is Best]

http://hadobs.metoffice.com/hadcet/cetml1659on.dat

3.5C making the final annual CET 9.96C

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

Wow they took their time!

Good to see the annual CET below 10C for the first time since 2001. Only 1996 was substantially cooler.

[Don]

Hurrah! Coldest December since 1996 and a sub 10C CET year. I wish (hope) this trend will continue for the next few years.

[J10]

The December CET figures will be updated this evening.

[Guest Mike W]

It's strange that they have the Annaul CET at 9.96 when I have done the calcualtion using the monthly CET figures they have and came up with 9.95, if anyone want sto double check that, it odd, becasue when i say 9.95 I mean it came up as 9.95 dead on.

[Thundery wintry showers]

It may well be hidden in the official stats as 9.96 rounds up to 10.0. Certainly a cool year by recent standards, though up on the long-term average- a fraction warmer than 2001.

This makes it the coldest December, alongside 2001, since 1996 according to Philip Eden's continuation of the CET, and the coldest since 1996 according to the Met Office version, as 2001 came in at 3.6C by both measures.

Note that according to Philip Eden's version the annual CET still sneaked in above 10.0C.

Edited January 9, 2009 by Thundery wintry showers

[Optimus Prime]

The average mean minima came in at 0.8c, 1.2c below average (October anomalay was also 1.2c below) and makes it the 34th coldest in history. Mean maxima was 1.0c below average and the 42nd coldest in history. Overall the 124th coldest ever.

[Snowly does it]

December 2008 is now the coldest month of the millenium as compared to the 71-00 mean at 1.6 below and is the first month at more than 1.5 below the 71-00 mean, and is in line with months such as December 96, Jan 97 or May 96.

January will need to come in at 2.5 or lower to take this accolade which has not been achieved since 1997 and only 16 times since 1900 - which should frame the reference for where December sits relatively speaking.

For the sake of completeness and assuming we sit at approximately 0 on the update for the 11th, the last 20 days of January averaging 3.9 would bring us in at about the same level below mean as December 2008 - so we still need to remain below average despite the sub zero start to maintain this level of cold set by December.

Thus twas a chill month.

[Guest Mike W]

I thought the coldest CET month of the millenium is Janaury 2001 at 3.2?

[North-Easterly Blast]

Rounded to 2 d.p the CET figure for Dec 2008 is 3.52*C, and for December 2001 3.56*C, so there is certainly very little in it, and certainly both were about the same, and the only colder Decembers since the 1960s were in 1976, 1981, 1995 and 1996. Also, the second half of December 2008 was warmer than the first half for the first time in 2002 and the third time since 1991.

Decembers in which the second half had a higher CET value than the first half since World War 2:

1945, 1947, 1949, 1951, 1952, 1954, 1957, 1958, 1959, 1960, 1966, 1971, 1973, 1974, 1975, 1977, 1980, 1982, 1983, 1987, 1988, 1989, 1990, 1991, 1997, 2002, 2008.

It was another very sunny December, certainly the second sunniest December on record and very nearly as sunny as December 2001. It is certainly a trend of the last ten years to have very sunny winter months. Take a look at these facts:

Winter 1999-2000 (Dec - Feb) the sunniest winter on record

January 2001 - second sunniest January on record

December 2001 - sunniest December on record

January & February 2003 - sunniest January / February pairing on record

Jan-April 2003 also sunniest such period on record

February 2008 - sunniest February on record

December 2008 - second sunniest December on record

In fact, every winter as a whole since 1996-97 has recorded sunshine above the long term average. In the last ten years the only winter month to record significantly below average sunshine was December 2002, whereas most other winter months have seen above average sunshine, with only a few others recording close to average sunshine values.

What could be the underlying reasons as to the significantly increased winter sunshine over the last decade?

[Snowly does it]

I thought the coldest CET month of the millenium is Janaury 2001 at 3.2?

In absolute terms yes but 3.2 is only 1 degree below the 71-00 mean. I am talking about how far below average the month is

[Bottesford]

Hurrah! Coldest December since 1996 and a sub 10C CET year. I wish (hope) this trend will continue for the next few years.

Yes if it involves proper winter cold months to drag that CET down and not just cool rubbish summers...

[Thundery wintry showers]

Mobile Atlantic weather (with a free-flowing stream of depressions rather than a jet locked into place by a Bartlett) tends to be wet but sunny, particularly in the east and south, due to the brighter weather in between rain belts and also the "sunshine and showers" associated with polar maritime air. Winter 1999/2000 was a notable case in point. It is worth noting that two of London's sunniest winters from the old days- 1951/52 and 1983/84- had a lot of mobile, polar maritime westerly and north-westerly types.

The other factor has been a high incidence of high-pressure spells with minimal influence from either the Atlantic or the east, both of which tend to lead to stratocumulus trapped underneath an inversion. As a result we've ended up with a lot of clear sunny weather during these spells. Most recently in February 2008, we had an anticyclonic spell with high pressure mostly over or to the east of Britain, so although north and west Scotland and Ireland retained some Atlantic influence keeping sunshine totals down close to the average, most other regions had remarkable amounts of sunshine.

It was a similar story in early 2003, though on that occasion the exceptional sunshine was even more widespread with only the northwest corner of Britain largely missing out.

In January and December 2001 high pressure was centred a bit further north, so north-western Britain also had large sunshine excesses, but on the other hand some east-coast counties had only slightly above average sunshine as easterly winds featured on occasion. I recall parts of north and west Scotland recording well over twice the normal sunshine in January 2001, and quite a wide range of locations exceeded twice the average in December.

[Snowyowl9]

So it was 3.5c after all of that then.

January 1985/february 1985 were very sunny months as I remember,even february 1986 also had quite a few sunny days I can clearly remember despite all the snowcover during those 3 months.

[paul tall]

It's strange that they have the Annaul CET at 9.96 when I have done the calcualtion using the monthly CET figures they have and came up with 9.95, if anyone want sto double check that, it odd, becasue when i say 9.95 I mean it came up as 9.95 dead on.

Every +0.01º counts to the Climate Change Industry and taxation machine.

[AtlanticFlamethrower]

It's strange that they have the Annaul CET at 9.96 when I have done the calcualtion using the monthly CET figures they have and came up with 9.95, if anyone want sto double check that, it odd, becasue when i say 9.95 I mean it came up as 9.95 dead on.

Does this happen in any other year of the temperature record? Just 2008?

Perhaps it's a typo and they need to be contacted to change it.

[J10]

The results are finally in, well done to Stormforce10 and mountain shadow for getting the figure of 3.5c spot on.

Dec_2008_CET.xls

Dec_2008_CET__for_PDF_.pdf

Figures are available in PDF format and Excel as per usual.

[Stratos Ferric]

Rounded to 2 d.p the CET figure for Dec 2008 is 3.52*C, and for December 2001 3.56*C...

Strictly speaking that's an incorrect treatment. Averaging to 2dp's numbers stated at 1dp overlooks the margin of error present in the latter. At 1dp values are inherently +/- 0.049 (e.g. a reading of 1.3C might actually be anywhere between 1.25C and 1.34C), thus any average will be +/- the same amount. Hence, the gap between the values for the months you cite is well within the margin of error; either one might, in fact, have been the colder.

We had the same discussion two or three years ago when one or two were looking at fractional decreases in annual CET as indicative of an end to warming (that before 2007); the safe rule when averaging is always to move to 1sf less than the raw data, unless that data has itself already been rounded from more accurate reading.

[Guest Mike W]

the 1979-08 CET averages: Jan 4.3, Feb: 4.4, Mar: 6.4, Apr: 8.4, May: 11.6, Jun: 14.4, Jul: 16.6, Aug: 16.3, Sep: 14.0, Oct: 10.6, Nov: 7.1, Dec: 4.9, Annual : 9.92.

[WhiteXmas]

Nice to see a change in the recent trand of a above average CET's. Hopefully we will see a cooling trend which I mentioned previously a few months ago.

[johnholmes]

Strictly speaking that's an incorrect treatment. Averaging to 2dp's numbers stated at 1dp overlooks the margin of error present in the latter. At 1dp values are inherently +/- 0.049 (e.g. a reading of 1.3C might actually be anywhere between 1.25C and 1.34C), thus any average will be +/- the same amount. Hence, the gap between the values for the months you cite is well within the margin of error; either one might, in fact, have been the colder.

We had the same discussion two or three years ago when one or two were looking at fractional decreases in annual CET as indicative of an end to warming (that before 2007); the safe rule when averaging is always to move to 1sf less than the raw data, unless that data has itself already been rounded from more accurate reading.

whilst once the actual temperature has been read to 0.1C, and no one can read it to anything greater, nor is there any point. Unless you wish to have your computer led thermometer reading to umpteen decimal places, then the subsequent change to any more than 2 decimal places which some seem to think acceptable is wrong. In my view, well known on here, temperature should be left at 0.1C either read, averaged or whatever. To give more decimal places is to WRONGLY assign higher accuracy which is not there.

The meteorological world has for over 100 years used the system of 0.1 degree, yes at F it is a much finer gradation than 0.1C. However when the WMO (World Met Organisation), with the exception of our American cousins, changed to C, all data was corrected to 0.1C, actual, or any other.

Quite why there is so much fuss about whether the mean is .1C or .12C or whatever is beyond me.

Edited January 10, 2009 by johnholmes

[stewfox]

Quite why there is so much fuss about whether the mean is .1C or .12C or whatever is beyond me.

Why have £9.99 and not £10.00 ?

Annual CET of 9.99 or 10.00 , Visually looks different

Of course 1dp enough but can see why some may look for 2dp

[johnholmes]

means nothing to a scientist

based on the actual being to 1 decimal, the most it can be acceptable subsequently is 2 decimal places

scientific acceptance no more

[AtlanticFlamethrower]

Why is the CET 9.96, not 9.95, as the correct math says it should be?

If you don't think 0.1C matters, why don't we dispense with the thermometers and at the end of this year vote on what the Annual CET for 2009 should be. It will be a lot cheaper and it has an advantage - concensus science is never, ever wrong.

Making up numbers is corrupt. Once you start, where do you stop? It's the principle. The Met O has broken a principle.

Edited January 10, 2009 by AtlanticFlamethrower

[johnholmes]

Why is the CET 9.96, not 9.95, as the correct math says it should be?

I have no idea, please address your question to those who can answer

If you don't think 0.1C matters, why don't we dispense with the thermometers and at the end of this year vote on what the Annual CET for 2009 should be. It will be a lot cheaper and it has an advantage - concensus science is never, ever wrong.

stop being ridiculous. Have you tried to read a thermometer to nearer than 0.1C or even 0.1F, I spent 20 years doing both. Your conclusion is just simply a silly remark unless you are serious in which case it is a totally uncalled for smear on many thousands of scientists around the world.

Making up numbers is corrupt. Once you start, where do you stop? It's the principle. The Met O has broken a principle.

No one within the science community I know is doing anything corrupt, please withdraw that accusation.

mods this needs to be left in please

John Holmes