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December 2015 - 5 Years on


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Posted
  • Location: North Leeds
  • Location: North Leeds

A lot of talk about the 10 year anniversary of December 2010 and rightly so but it’s also 5 years since this nightmare month. The warmest December of all time by a ridiculous margin.

What are people’s overriding memories (or nightmares) of this month? Mine is the warmth in the week before Christmas, I remember driving home from work in short sleeves and the temperature being 17C on about the 18th which felt wrong on every level and I like warm weather. 

It’s also the only time I can remember when my local area flooded, this was caused by the constant rain that started on Christmas Day and continued all of Boxing Day. The attached picture was taken on the 28th in Esholt near Bradford but it was a lot worse in other areas.

It was awful but memorable month (for all the wrong reasons!)

6BA05AB2-F235-4A23-B6BC-AE216FA787CA.png

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Posted
  • Location: Home: Chingford, London (NE). Work: London (C)
  • Weather Preferences: Winter: cold and snowy. Summer: hot and sunny
  • Location: Home: Chingford, London (NE). Work: London (C)

The whole period from 2013/14 to 2016/17 had dire winters. Mild, wet, very little in the way of cold, barely any snow. What a horrid period of winter weather.

2017/18 was an improvement with a heavy December snowfall down here and then the Beast form the East in Feb/March. 

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Posted
  • Location: Edmonton Alberta(via Chelmsford, Exeter & Calgary)
  • Weather Preferences: Sunshine and 15-25c
  • Location: Edmonton Alberta(via Chelmsford, Exeter & Calgary)

do you know what i was glad it was the warmest Dec on record..i was living in Ruislip at the time and my boiler broke down took two weeks to get a new one installed..so for me it was a result it wasn't cold outside

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Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

I recently posted this in the CET contest thread ...

It's interesting that Dec 2015 is also the warmest on record for both Toronto (181 years of data) and NYC (152). It moved ahead by similar margins too. At Toronto, Dec 2015 averaged 5.2, while the previous high was 3.2 (2011). At NYC (Central Park) Dec 2015 averaged 10.4, the same month (2011) was second there but a full 3.7 C deg cooler at 6.7. Both of these locations need an urban heat island correction to compare to early period data but after applying that correction these months remain 1-2 anyway, albeit some earlier ones move into the top ten.

Not hard to see that something very unusual was happening in the western hemisphere generally speaking in Dec 2015, and it certainly began in Nov 2015 which was also very mild in all these areas although not top November in any (this past November has moved into first place for NYC and fourth for Toronto which had its warmest Nov in 1975). 

Perhaps a key event was the northward heat transfer achieved by super-hurricane Patricia which moved into Mexico from the Pacific around Oct 24 and spawned a deep low over the Gulf of Mexico which then moved through the Great Lakes region on the 28th giving Toronto a record daily rainfall. 

After that, it seems that very warm weather for time of year persisted anywhere to the east of this low's track, for about three months. The warm spell was absurd in some places, southeast Virginia had readings in the mid-80s (F) around Christmas 2015. The spell broke down with a very heavy snowstorm across the eastern U.S., places around Washington DC had 25-30 inch amounts from this (in mid-January 2016). The UK warmth persisted longer, with late January 2016 setting new daily records and tying the monthly CET (daily mean) record. 

Another key antecedent event may have been the polar vortex winters of 2014 and 2015. In the second of these (2014-15) temperatures were exceptionally cold in February 2015 in eastern and central North America. It was the third coldest February on record at Toronto even before heat island correction applied (that did not move it past 1, 2 which are 1875 and 1885). The weather stayed rather cold in North America for most of 2015 until that reversal mentioned in Nov and Dec. Possibly a factor where in this warming climate any sustained cold regime like that must be holding back a considerable building reserve of warmth to come, sort of like throwing ice cubes into a pot of almost boiling water. 

On the other hand, Dec 2010 was not as particularly cold in North America although it was slightly colder than recent averages (Toronto -2.8, rank overall was tied 70th coldest out of 180, adjusted by urban heat island, moved to tied 49th coldest. The winter went on to produce a number of memorable snowstorms however, which is rare in recent decades. 

(and from another part of the same thread, running CET values for 2015 edged ahead of the pack in mid-month and never looked back, the closest any month came in the late stages was 1898 reaching about 8.9 around 21st ... 2015 finished 9.7, the former record was a tie (1934, 1974 at 8.1). This is the widest margin of any first place month although May 1833 is close (15.1 to 13.9). 

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Posted
  • Location: Irlam
  • Location: Irlam
22 hours ago, danm said:

The whole period from 2013/14 to 2016/17 had dire winters. Mild, wet, very little in the way of cold, barely any snow. What a horrid period of winter weather.

2017/18 was an improvement with a heavy December snowfall down here and then the Beast form the East in Feb/March. 

Up here, I would take out 2014-15 from that list. It wasn't too bad. CET wise it was only 0.2C warmer than 2017-18. Seems to be forgotten this winter. 

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Posted
  • Location: Home: Chingford, London (NE). Work: London (C)
  • Weather Preferences: Winter: cold and snowy. Summer: hot and sunny
  • Location: Home: Chingford, London (NE). Work: London (C)
4 minutes ago, Weather-history said:

Up here, I would take out 2014-15 from that list. It wasn't too bad. CET wise it was only 0.2C warmer than 2017-18. Seems to be forgotten this winter. 

I think the run between 2013/14 and 2016/17 was the worst in terms of lack of cold and snow, in my lifetime (since 1986) down here. In London we barely had any snow in that 4 year period. Oddly, It came off the back of 5 straight winters where we had our fair share of snow, between 2008/09 and 2012/13. 

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Posted
  • Location: North Leeds
  • Location: North Leeds

Yeah up here in Yorkshire 2014-2015 was actually alright, we had snow on Boxing Day and then several snowy spells in January and February. December 2015 was so bad it dragged the whole winter down even though we did have cold and snow in January and February 2016, I’ll agree it was good for heating costs that December though!

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Posted
  • Location: Clacton-on-Sea, Essex
  • Location: Clacton-on-Sea, Essex

I remember posting a picture of my lawn on Facebook in that month, covered in daisies and dandelions.  If it had been dry enough I would have cut the grass as it was so long!  

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Posted
  • Location: Edinburgh (previously Chelmsford and Birmingham)
  • Weather Preferences: Unseasonably cold weather (at all times of year), wind, and thunderstorms.
  • Location: Edinburgh (previously Chelmsford and Birmingham)
16 hours ago, Roger J Smith said:

(and from another part of the same thread, running CET values for 2015 edged ahead of the pack in mid-month and never looked back, the closest any month came in the late stages was 1898 reaching about 8.9 around 21st ... 2015 finished 9.7, the former record was a tie (1934, 1974 at 8.1). This is the widest margin of any first place month although May 1833 is close (15.1 to 13.9). 

On this point, it's worth noting that the Winter months see more variability about the mean than May. The series mean for May is 11.24C with standard deviation 1.15C, while for December we have 4.12C and 1.75C, respectively. One finds that the relative anomaly for May 1833 is actually greater than December 2015 (3.36 standard deviations vs 3.19).

Of course, the months aren't normally-distributed, but it's not too unreasonable an approximation to make.

Edit: if you go a little further you find that May has a slightly positive skewness of 0.09 while December has a more negative skewness of -0.29, so overall it's a pretty close contest between the two months when it comes to the "most outrageous positive anomaly" award.

Edited by Relativistic
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Posted
  • Location: Edinburgh (previously Chelmsford and Birmingham)
  • Weather Preferences: Unseasonably cold weather (at all times of year), wind, and thunderstorms.
  • Location: Edinburgh (previously Chelmsford and Birmingham)

So it turns out the most anomalous month by the above measure is actually June 1846, whose value of 18.2C is 3.56 standard deviations above the series mean of 14.33C. May 1833 ranks second, and August 1995 at 19.2C ranks third, being 3.29 standard deviations above the series mean of 15.65C.

In fact, December 2015 only ranks in fifth place, just behind July 2006, which was 3.19 standard deviations above the series mean of 15.99C. Relative to January, February, and March (those months for which the series skew is appreciably negative), though, it wins quite convincingly. January 1916, for example, is only 2.13 standard deviations above its 3.27C series mean. January also has the most negative series skew, at -0.60.

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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL
5 hours ago, Weather-history said:

Up here, I would take out 2014-15 from that list. It wasn't too bad. CET wise it was only 0.2C warmer than 2017-18. Seems to be forgotten this winter. 

Yes because it was crap and damp.

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Posted
  • Location: Dublin, Ireland
  • Weather Preferences: Cold, snowy winters and warm, sunny summers
  • Location: Dublin, Ireland

2014-15 was my sunniest winter on record which I'd take in a heartbeat if it's not going to be snowy. 2017-18 was my second sunniest. Theme with both? Very northwesterly. Had -8C on 3 February 2015 too which is my lowest temp from 2011 to present. 

As for the thread, I quite enjoyed the extremity of December 2015 which I know is an extremely unpopular opinion (of course I'd much rather the December 5 years prior)! Second wettest of any month on record in Dublin behind only December 1978. None of the storms were that notable for wind but similar to February 2020, often very windy. Storm Desmond was easily the "highlight" (or should that be lowlight?) of the month for the country but I was in a rain shadow so escaped a lot of the rain as I typically do in a long fetched southwesterly.

Edited by BruenSryan
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Posted
  • Location: Carmarthenshire
  • Location: Carmarthenshire

A 10.4C difference in the CET for the same month within 5 years between 2010 and 2015 is quite something.  To put that in perspective, if we had a July that was 10.4C warmer than the coldest in the series, we'd end up with 23.8C!  There is a similar gap between the warmest and coldest Januaries but 

December 2015 was awful here though: the wettest month in the last decade by quite some margin and zero dry days.  Much preferred 2010!

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

Yeah I enjoyed 2014/15 mainly because of the high frequency of polar maritime air masses.  There were also some snow events from the Midlands northwards, although as with many such "westerly" winters there wasn't much lying snow around in the south.  

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Posted
  • Location: Edinburgh (previously Chelmsford and Birmingham)
  • Weather Preferences: Unseasonably cold weather (at all times of year), wind, and thunderstorms.
  • Location: Edinburgh (previously Chelmsford and Birmingham)
4 hours ago, Daniel* said:

Yes because it was crap and damp.

Enjoyed it in Birmingham. Felt very seasonal with plenty of frost and frequent snow events, albeit not major ones. In late January and early February the local canal was often iced over in the mornings.

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Posted
  • Location: Sheffield
  • Weather Preferences: Sunny and dry, thunderstorms, mild temps (13-22°C).
  • Location: Sheffield

Fantastic month. I lived in a cold, draughty apartment at the time, so it was good to have that mildness for me personally. I also lived in Buxton then, one of the highest towns in England, and I believe that month was the only winter month in Buxton's history to have a double figure average max temperature. Quite a feat for that location!

Edited by Thundershine
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Posted
  • Location: Edinburgh (previously Chelmsford and Birmingham)
  • Weather Preferences: Unseasonably cold weather (at all times of year), wind, and thunderstorms.
  • Location: Edinburgh (previously Chelmsford and Birmingham)
3 hours ago, virtualsphere said:

A 10.4C difference in the CET for the same month within 5 years between 2010 and 2015 is quite something.

A remarkably similar thing happened for January, only it was just the one year that separated them.

 

January 1795: -3.1C (coldest on record)

January 1796: 7.3C (joint-second mildest on record)

 

So the same 10.4C difference, and also the same difference in the ranks (Decembers 2010 and 2015 are respectively the second-coldest and mildest on record).

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Posted
  • Location: North Leeds
  • Location: North Leeds

I had my works Christmas do on the 15th and I remember stood outside in a queue to a bar at about 2am literally sweating. The wind was so warm, it felt like being abroad! It was staggering especially it was 5 years after 2010 like others have mentioned.
 

The named storms we had were not particularly memorable here, the rain event on Boxing Day followed on behind “Eva”. Probably the wettest 24 hours I can remember.

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Posted
  • Location: Crymych, Pembrokeshire. 150m asl
  • Weather Preferences: Extremes of all kinds...
  • Location: Crymych, Pembrokeshire. 150m asl

Sorry - wrong thread!

Edited by Sky Full
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Posted
  • Location: Irlam
  • Location: Irlam
18 hours ago, virtualsphere said:

A 10.4C difference in the CET for the same month within 5 years between 2010 and 2015 is quite something.  To put that in perspective, if we had a July that was 10.4C warmer than the coldest in the series, we'd end up with 23.8C!  There is a similar gap between the warmest and coldest Januaries but 

December 2015 was awful here though: the wettest month in the last decade by quite some margin and zero dry days.  Much preferred 2010!

27th November-27th December 2010: -1.5C

27th November-27th December 2015:  9.5C

 

 

Edited by Weather-history
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Posted
  • Location: Bratislava, Slovakia
  • Location: Bratislava, Slovakia

It really was the anti-December 2010, so bad that I could no longer say I'd been spoilt by that legendary winter month - because 2015 more than cancelled it out.

An overnight frost sometime around the 12-13th is the only thing stopping December 2015 from scoring 0/10.

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Posted
  • Location: Bratislava, Slovakia
  • Location: Bratislava, Slovakia

Another amazing thing - November that year was the third-warmest on record and December was still warmer than it. In fact, there has only been one warmer November than December 2015 in the entire CET record. It was also warmer than any March. 

It's like recording a November as cold as December 2010 (beaten only by one other December). 

Edited by AderynCoch
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Posted
  • Location: Ossett, West Yorkshire
  • Location: Ossett, West Yorkshire
On 01/12/2020 at 16:58, danm said:

The whole period from 2013/14 to 2016/17 had dire winters. Mild, wet, very little in the way of cold, barely any snow. What a horrid period of winter weather.

2017/18 was an improvement with a heavy December snowfall down here and then the Beast form the East in Feb/March. 

In all winters since 2012-13, only winter 2017-18 brought anything close to an average winter, with most others being in the very mild category.  Adding on top of this, most winters of the last 33 years have been milder than what would have been average prior to that.

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