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In Reading, based on obs so far this month and the
forecast temps until the end of the month using GFS model forecasts,
the mean temperature for December is heading towards 10.9C, some
5.8 degC above the `981-2010 normal.

The warmest Decembers since 1908 have been those pf
8.5C 1934
8.1C 1974
7.6C 1988
i.e. some 2.4 degC colder at best.

while the normal is 5.1C. No other month
has ever has a positive anomaly above 3.9 degC
with respect to 1981-2010!

Roger

On 19th Dec I recorded a new daily maximum for this location of 15.7C, previous maximum for a December day was 15.0C in 1997. I have also recorded a new 21-09hrs record high minimum air temperature of 13.2C at 06:00hrs on the morning of the 26th, previous high minimum was 12.9C in December 2001. Mean air temperature for December is 5.0C, as of 27th currently this stands at 11.1C

Regards

Have just had 42 straight hours with the air temp above 13.5c. Doesn't feel like the holiday season at all.

Minimum temperature of 12.8C this morning in Reading was the
highest 09-09 GMT minimum in 108 years of records in December.

Other 18-06 GMT minima this morning include
13.7C at Benson
13.7C at Northolt
13.8C at Heathrow
13.3C at Maidenhead

No air frost yet this December in Maidenhead or Reading

Roger

Rob Overfield wrote:Have just had 42 straight hours with the air temp above 13.5c. Doesn't feel like the holiday season at all.

I've just check and the temperature here has been above 13.5°C for the last 51 hours (up to 14:00 on the 27th).

Minimums and maximums so far for today and yesterday:
26th 13.7°C 15.0°C
27th 13.7°C 14.8°C

December monthly mean temperature is now at 11.5°C but the real anomaly-breaker is the mean minimum which is currently at 9.4°C, that is over 5.0°C warmer than my very estimated LTA.

No air frosts so far and only one grass frost with -0.6°C on the 9th.

Min temp here at Farnborough on the 26th (00-00) was 13.1C (this is 0.7C above the average July min!)

Mean max temp for Dec (1-26): 13.1C
Mean min temp for Dec (1-26): 8.7C
Mean temp for Dec (1-26): 10.9C

Certainly in the record-breaking territory for warmth! But no unusual rainfall here in the SE. I have only measured 33.5mm so far in December.

In Penzance (1st-26th)
Mean Max 13.5C
Mean Min 10.7C
Mean 12.1C

The previous warmest Decembers in my record, which starts in 1991 were 1994 & 2007 at 9.3C.

So it is currently my warmest ever December by 2.8C!

Attached photo of St. Ives on Xmas Eve. In the sunshine it felt more like September than December, plenty having a paddle in the sea, not the way you normally plan a Christmas break in Cornwall! Not too much rain here, so far 135.8mm or 95% of the 1981-2010.

Graham Easterling wrote:In Penzance (1st-26th)
Mean Max 13.5C
Mean Min 10.7C
Mean 12.1C

And here (1st - 27th):
Mean Maxumum: 13.6°C
Mean Minimum: 9.4°C
Mean: 11.5°C
Rain 64.7 mm
Sunshine = 46 hours.

Whilst the mean minimum is remarkable in itself for this river valley location, it is even more remarkable when you consider that most of the lowest temperatures recorded were only briefly 'low' during those short night-time breaks in the cloud and lull in the wind. The integrated mean temperature is 11.7°C, normally at this time of year the integrated temperature is much lower than the daily average.

The annual mean temperature for 2015 is now at 11.7°C, well down on last year's 12.1°C but still above normal.

Still mild at this station with only one air frost, and three ground frosts.


Mean Max: 11.5c

Mean Min: 6.3c

MEAN: 8.9c

Anomaly: +4.4c

... as now well-known, we've finished with December 2015 being notably (dramatically?) mild; the CET (350+ years record - early years/decades low resolution) looks to be 9.8degC (data to 30 DEC), which breaches the previous joint-record years' [1934 & 1974] value of 8.1degC by a large margin.

Usually when we look at 'new records' over a monthly mean, the differences are assessed in tenths of a degree C. This December just gone has exceeded the previous value by over 1.5C!

In the local (Hurn) record [begins 1957], the provisional mean for December 2015 = 11.5, beating the previous record-breaker (1974/8.5degC) by 3C!!

Third month with below-average sunshine; November (41% LTA) & December (52% LTA) were notably sunless - several days at a time with no sunshine observed. We're all looking a bit 'pasty-faced' hereabouts!

Martin.