December 2009 Summary

Temperature [Max]:
The average daytime temperature this month was 10.33 degs C, making it the coldest December here since I started in 2003. The coldest day itself was the 18th with a max of 3.9 degs, and was the coldest December day ever recorded here as well. The highest temperature of the month was 14.8 [9th] which was conversely, the third warmest December day since 2003.
The mild and cold weather alternated throughout the month: mild until the 11th with highs in double figures, thereafter in single figures [bar one day] until the milder weather returned from the 25th to the 30th.

Temperature [Min]:
Nighttime temperatures averaged at 4.72 degs C, which is the lowest for December ever recorded here. The coldest night [18th/19th] saw a minimum of -2.5 degs - which also was the coldest ever for December. The highest minimum was 11.0 [8th/9th].
There were 15 nights during the month when the temperature fell below 5 degs C, the most ever for December, and 2 nights below zero - the most again, equal with 2005.

Rainfall:
144 mm of rain fell during the month, 44 mm of which fell on the 29th, which was also the wettest day of 2009 and indeed the wettest day since 9th July 2008.
This compared to 83.3 mm during December 2008. There were only 6 completely dry days during the whole month, however there was a long dry spell from the 9th to the 18th when only 1.8 mm of rain fell in total.
Most significantly, rain fell onto freezing surfaces during the morning of the 22nd, causing widespread black ice which lasted for two days.