December CET

[North-Easterly Blast]

You mean frozen out

The longest gap between sub-zero CET months is still Feb 1895 to Jan 1940

That's one record that will be safe until at least 2056

Yes very true, although in recent years we have broken and set a number of long interval records for numerous cold thresholds:

The longest interval between months without a sub 2*C CET is 18 years 11 months (Feb 1991 to Jan 2010)

The longest interval between months without a sub 3*C CET is 13 years 0 months (Jan 1997 to Jan 2010)

The longest interval between months without a sub 3.5*C CET is 8 years 0 months (Jan 2001 to Jan 2009)

All the above cold threshold records have been set in recent years, but as we had a sub zero CET as recently as Feb 1986, that 45 year record has remained in tact.

On top of the above, as I have mentioned about the strokes of luck required in not getting short mild spells to break it all up, we almost managed a sub 2*C in December 1995, as the period from the 4th to 31st of that month averaged 1.6, or more precisely 1.56*C; it was only three mild days at the start of that month that pushed the CET over 2*C. As February is a shorter month, there are three fewer days (or in leap years two fewer days) that the CET has to stay low enough to maintain a low CET, a period of 28 days in Dec 1995 (the same length as the month of Feb) averaged below 2*C.

Edited January 2, 2011 by North-Easterly Blast

[kold weather]

-0.7C

Wow.....

Well there you have it folks, we have lived through a really historic month, its amazing to see such a negative anomaly.

I was thinking Jan 2010 may have been the cold point for at least the next few winters...but December 2010 was on another level of cold...Ja 2010 was a Championship winter month...whilst December 2010 is a Champions league month!

All this whilst the globe is at record breaking temps...just proves that we CAN still go sub zero even with the globe being very warm....

Just proves that there are far bigger factors at play then just AGW in our weather locally in NW Europe. it was just pure chance that NW Europe saw a big warm up in the synoptic evolution as the pattern became condusive for strong warming (The PDO and AMO both going positive plus strong Solar Maxes, combined with the obvious background AGW signal) but as soon as we start to lose that forcing to some extent guess whats happened...yep NW Europe has showed steady cooling from the peak warmth of the mid 00s...

[reef]

-0.7C

Wow.....

Well there you have it folks, we have lived through a really historic month, its amazing to see such a negative anomaly.

I was thinking Jan 2010 may have been the cold point for at least the next few winters...but December 2010 was on another level of cold...Ja 2010 was a Championship winter month...whilst December 2010 is a Champions league month!

All this whilst the globe is at record breaking temps...just proves that we CAN still go sub zero even with the globe being very warm....

Just proves that there are far bigger factors at play then just AGW in our weather locally in NW Europe. it was just pure chance that NW Europe saw a big warm up in the synoptic evolution as the pattern became condusive for strong warming (The PDO and AMO both going positive plus strong Solar Maxes, combined with the obvious background AGW signal) but as soon as we start to lose that forcing to some extent guess whats happened...yep NW Europe has showed steady cooling from the peak warmth of the mid 00s...

It makes you wonder how cold December 2010 would have been if background global temperatures were as they were in 1890 (some 0.8C cooler than now). I imagine we'd have been looking at more like close to -1.5C, which makes the month even more remarkable.

[Weather-history]

The CET average for those periods that were at least 10 consecutive days of sub-zero CET means in length and that averaged -3.50C or less

17th-27th Dec 2010: -3.93

6th-15th Jan 1982: -4.03

7th-26th Jan 1963: -3.56

20th-29th Jan 1945: -3.52

5th-18th Feb 1895: -4.81

8th-27th Jan 1881: -4.38

21st Dec 1870-4th Jan 1871: -4.11

6th-23rd Feb 1855: -3.71

8th-21st Jan 1838: -5.14

8th-17th Jan 1826: -3.7

3rd-16th Jan 1820: -3.57

10th-26th Jan 1795: -3.79

Edited January 2, 2011 by Mr_Data

[kold weather]

Indeed Reef, then again I think for once the difference wouldn't have been much, the severe last 10 days or so of November really took down the North Sea and Channel temps and so the SST's across N.Europe as well as the soil profiles were proably every bit as cold as they would have been in say 1890, though the Arctic air probably was warmer then it otherwise woul have been...but even so I don't think it'd have been that much colder then this really...

Still the fact we had a 30 day period at -1.5C suggests that in theory we probably could have a month as cold as Jan 63...which as exceptional as December 2010 has been, is still the benchmark for severe cold!

[damianslaw]

A truely superb winters month and a fantastic statistic - never thought I'd see the day such a low CET value was recorded.

It was the cold mins rather than maxes which did the job. We had many days with very light winds and cloudless skies and we ended up developing our own unique cold pool especially during the second part of the month in the run up to christmas. Seeing the cold pool over the Irish Sea not going anywhere was very unusual indeed.

I thought last January would be the best we could hope for..

What was also very unusual was how early the cold developed in late November after a not particularly first half to the month, it is normally January or February when sustained cold sets in, though things have been quite unusual for three years now with lots of cold weather in laet Nov 2008 and early Dec 08 and then late Dec 08 and then the second half of Dec 09.

[Isolated Frost]

Indeed, very nice month, so early on.

The first cold spell gave Severe Cold and Snowfall for Scotland, NE England and much of the Eastern Coastline.

The second gave the most luck elsewhere, and the SE again.

[Summer of 95]

-0.7;. Quite a downward adjustment (Eden says -0.5) but whichever you believe, it's a subzero month. December 2010, take your seat at the top table alongside Jan and Feb 1963, Feb 1947, Jan 1979, Feb 1986, Jan 1940 etc.

I can't remember a thing of the weather in February 86 (can remember one or two things that happened then, but not any snow or ice that I can definitely date to that month) so it's my first clear memory of a sub-zero CET. Ands like many oithers, in 2007 and 2008 I doubted that I'd ever see any CETs below 2C again.

Is it exaggerating it to say "The coldest December since the Little Ice Age"? Have seen dates varying from about 1820 to 1900 given for the end of the LIA.

And -1.5C for Northern Ireland, what was that about the west being warmer in winter? Proves it was a UK-wide historic month. Truly one to talk about in years to come, feel privileged to have experienced it.

Now what can January and February bring??

[scottishandy]

I know it's not strictly related but does anyone have an equivalent to the CET for Scotland? I know it's been cold but would be good to see some figures on just how cold.

[Norrance]

I know it's not strictly related but does anyone have an equivalent to the CET for Scotland? I know it's been cold but would be good to see some figures on just how cold.

The Met Office publish regional average temperatures. Don't think that it is up yet though they sometimes have a summary in advance. When you see the latest past show December values go into the regions. It is split into various parts of the UK and within Scotland gives East, North, West and South/ Central.

[Summer of 95]

Yes very true, although in recent years we have broken and set a number of long interval records for numerous cold thresholds:

The longest interval between months without a sub 2*C CET is 18 years 11 months (Feb 1991 to Jan 2010)

The longest interval between months without a sub 3*C CET is 13 years 0 months (Jan 1997 to Jan 2010)

The longest interval between months without a sub 3.5*C CET is 8 years 0 months (Jan 2001 to Jan 2009)

All the above cold threshold records have been set in recent years, but as we had a sub zero CET as recently as Feb 1986, that 45 year record has remained in tact.

Is the 23 years 11 months Jan 1987-Dec 2010 also the record interval between sub 1C? Can see a gap of precisely 22 years (Feb 1895-Feb 1917) but nothing larger.

[J10]

I know it's not strictly related but does anyone have an equivalent to the CET for Scotland? I know it's been cold but would be good to see some figures on just how cold.

http://www.metoffice.gov.uk/climate/uk/datasets/index.html# should help with some of the figures.

[Optimus Prime]

http://www.personal.dundee.ac.uk/~taharley/2010_weather.htm

Review from brit weather years.

30 year average 1981-2010 stands at 4.6c.

1971-2000 5.1c

1961-1990 4.7c

2000-2010 4.26c

1960-1970 3.55c

[ZONE 51]

Just amazing! and did we ever think it could happen in modern times...the winters of more warmth then cold, and here we are breaking records!

[Roger J Smith]

This month has demonstrated that the scoring system in use here contains a flaw, because there is no way people entering on the 5th should get more points than reasonably close forecasts submitted before the end of the month.

Personally, I don't think any entries should be accepted after the 2nd of the month. But if they are, the penalties need to be in percentage terms, not points that can be traded in on bonus points for accuracy as happened here.

If you look at the column marked "ave acc" you'll see what I mean -- there are huge bonus points there which are about one quarter of all points available, and the penalty points are smaller than this category alone.

This "ave acc" stat should be scrapped, just add the bonus points to the other columns and to make things more proportionate, raise the late penalty to 20 points a day (I always thought it was 10% not 10 points out of a possible 300).

Congrats to the guys who entered on time and guessed below zero, that was pretty sharp forecasting. Some of the other stuff is just sharp practice.

[Snowyowl9]

A truely superb winters month and a fantastic statistic - never thought I'd see the day such a low CET value was recorded.

It was the cold mins rather than maxes which did the job. We had many days with very light winds and cloudless skies and we ended up developing our own unique cold pool especially during the second part of the month in the run up to christmas. Seeing the cold pool over the Irish Sea not going anywhere was very unusual indeed.

I thought last January would be the best we could hope for..

It was the cold pool and light winds that helped very much so,although there were some very low daytime maxes also many more than last winter even from late november.December 1981 type month.

I didn`t think it was the warmest globally I heard it was about the 4th warmest where did that come from.

Just shows how cold it`s been at -0.7c where theres still thick ice still left over from november,nevere seen that happen before,makes it extremely remarkable if thats the case(warm glabally)

So the coldest month since feb 1986 this month did have almost double the amount of snow but Feb 1986 was IMO still unbeatable thanks to a 10 fold more strong easterlies.

Not a bad guess then,wish I`d of a guess for Jan about 2.5c cold zonality it looks more to me this year.

Edited January 3, 2011 by Snowyowl9

[Weather-history]

The absolute value may be a little down the list on coldest months on record but if you think about it in terms of ranking, December 2010 surpasses Feb 1986 and even Jan 1963.

It is the 2nd coldest December on record for the CET whilst Jan 1963 and Feb 1986 were "only" the 5th coldest in their respective rankings.

The last 4 or 5 years we have had some pretty remarkable extremes in terms of sunshine, temperature and rainfall.

Off the top of my head

Warmest April on record

Warmest July on record

Warmest September on record

Warmest year on record

Warmest autumn on record

2nd coldest December on record

Sunniest February on record

Dullest August since 1912

4th driest April on record

2nd wettest June on record

Wettest May-July period on record

4th wettest November on record and the 5th wettest month ever recorded

[kold weather]

Well when you have a lobe of the PV come down from the Arctic and actually sit over the UK itself your going to get a very cold set-up and usually get a very cold CET return.

It's so cool though to see a negative figure on the CET records...and indeed its a pretty solid negative number as well...a month as cold as Feb 63...thats pretty stonking really!

[Anti-Mild]

About 4 years ago I posted a poll asking whether it was possible to get a sub zero CET month in this country. If I remember correctly 30% suggested it could happen again, including myself, although if they were like me they didn't truly believe it - it was more like hope!

Who would have thought that it would happen so emphatically with the second coldest December ever and the 23rd coldest month since records began!

Quite amazing really, especially coming on the back of a very cold winter last year, and, let's not forget, that now makes 7 consecutive below average winter months.

[Lake District Blizzard]

What is even more amazing is there is only 4 months with a lower mean minimum CET, being

Feb 1895, -5.1

Jan 1963, - 4.8

Jan 1940, -4.5

Jan 1881 -4.3

December 2010, -3.8

Feb 1947, -3.8

[Upgrade]

What is even more amazing is there is only 4 months with a lower mean minimum CET, being

Feb 1895, -5.1

Jan 1963, - 4.8

Jan 1940, -4.5

Jan 1881 -4.3

December 2010, -3.8

Feb 1947, -3.8

Yes, December 2010 is undoubtedly up there with "the greats", those cold months of your grandparents' stories. We beat December 1981 for cold and snowyness. Fantastic. Loved every minute ( nice to have a few days now where i don't need to wear 3 pairs of socks and 2 pairs of gloves though ).

2 big dumps and 12 (at least ) days of lying snow in London - pretty special, with the powder snow, "pisted" pavements and roads, and the buildings plastered with icicles and snow for days on end. Seeing truly breathtaking sights of a foot of snow in the southern suburbs, looking like lapland, and great and unusual sights throughout town really. Cycling across the snowy parks to work every day was magical. Drifts on the North Downs still there on 1 Jan. Wonderful stuff.

Edited January 3, 2011 by Upgrade

[summer blizzard]

The absolute value may be a little down the list on coldest months on record but if you think about it in terms of ranking, December 2010 surpasses Feb 1986 and even Jan 1963.

It is the 2nd coldest December on record for the CET whilst Jan 1963 and Feb 1986 were "only" the 5th coldest in their respective rankings.

The last 4 or 5 years we have had some pretty remarkable extremes in terms of sunshine, temperature and rainfall.

Off the top of my head

Warmest April on record

Warmest July on record

Warmest September on record

Warmest year on record

Warmest autumn on record

2nd coldest December on record

Sunniest February on record

Dullest August since 1912

4th driest April on record

2nd wettest June on record

Wettest May-July period on record

4th wettest November on record and the 5th wettest month ever recorded

Was July 2006 not the sunniest month on record as well, and did we not have the warmest spring on record?

Where did December 2010 stand in terms of sunchine and precipitation, because it was an exceptionally dry and sunny month here.

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

December 1890 had zero sunshine in London, it certainly wasn't that dull this time round! And only 0.1C higher CET!

[North-Easterly Blast]

I am dubious as to why Hadley have put a value as low as -0.7 for the December 2010 CET. If you look at an alternative series (England Mean Temperature) from 1914, you will see in that series December 2010 is listed as having a mean of -0.5.

I know that the CET, and the England Mean Temperature series from 1914 are two different series, however, I find this a good guide to identify anomalously low - or high, CET values that are listed for each month. In general, the England Mean Temperature series from 1914 has most months slightly cooler than the CET. Very occasionally, a month has the same value for both the CET and the England Mean Temperature series. I cannot find any month that has registered a lower CET value than the value listed in the England Mean Temperature series from 1914 - now Dec 2010 is a case where the CET is 0.2 lower than the value in the England Mean Temperature series - this has never happened before. Look at Dec 1981 - 0.2 for the England Mean Temperature and 0.3 for the CET. Jan 1979 had the same value for both the CET and the England Mean Temperature series. Look at Feb 1963 - -0.7 for the CET and -1.2 for the England Mean Temperature.

I now raise a question as to a possible mistake in the Dec 2010 CET. Judging by this alternative England Mean Temperature series, I believe that the Dec 2010 CET should be nearer -0.5 or -0.4 - not the -0.7 that is listed for the CET, with the England Mean Temperature series registering a higher value. If there is not a mistake in the CET figures for Dec 2010, it is certainly an anomalously low value that Hadley have put down for the Dec 2010 CET.

[Thundery wintry showers]

The CET samples a relatively limited area of England whereas the England Mean Temperature is derived from stats from all over England, so there are bound to be anomalies. The Midlands and north-west England were the two most anomalously cold regions of England during December 2010, so this will have had an effect on the CET.

One remarkable facet of December 2010 was that it was made up of two severe cold spells interspersed with two milder interludes, whereas many other severe cold months have been marked by consistent cold and absence of anything significantly milder- February 1986 and February 1947 for instance.

Sunshine wise it was dull in SE England (only 19 hours at Heathrow), though nothing like as dull as December 1890, while it was a sunny month elsewhere, exceptionally so in some regions. Precipitation was much below normal in most regions although, as Philip Eden points out, there are question marks against the precipitation figures because the vast majority of it was snow and there are issues with measurements of melted snow at automated sites.