January 2011 Summary

Summary:
January 2011 began with generally lower temperatures than those with which December 2010 ended, particularly at night, before becoming much milder, but very wet, until the 17th.
Much drier, sunnier and colder weather then followed, although it was slightly less cold again around the 23rd to 26th with a little more rain. It then became dry again, but this time very cold with mainly cloudy skies for the last 5 days.
This colder weather was brought about by the wind being in the north-east or east for the last two weeks of the month, thereby cutting off the flow of more common mild south-westerly winds off the Atlantic. The north-easterly winds also led to the persistent cloud reported in the south-east of England being much less prevalent, particularly in the penultimate week, due to the high ground of Dartmoor and Bodmin Moor to the north-east.

Temperature [Min]:
Night time temperatures were in the range -2.5 degs C [on the nights of 29th/30th and 30th/31st] to 11.9 [12th/13th]. This equals [with 20th January 2008] the mildest January night ever at this location*.
The average night time temperature for the month was 4.4 degs C which is the second coldest for January recorded here* - 2010 was the coldest at 2.73.
The temperature fell below 5 degs C on 17 nights and below 0 degs C on 5 - both these figures are the second highest ever for January* and again 2010 had the highest with 23 and 9 times respectively.

Temperature [Max]:
Daytime temperatures were in the range of 4.2 degs C on the 28th, and 13.4 on the 12th. This maximum is the equal [with February 2009 and 2010] second lowest temperature ever reached in any month at this location*. In January 2009 the temperature did not rise above 13.3 degs C.
The average maximum temperature for January 2011 was 9.83 degs C, which is the second lowest ever for January at this location* - and again the lowest itself was 2010 [8.33].

For both night and day temperatures, January 2011 was therefore the second coldest January behind 2010.

Rainfall [Max]:
180.2 mm of rain fell during January 2011, with 174.2 mm of the total falling by the end of the night of the 17th/18th. This compares with 183.8 mm in November 2010, and 116.9 mm in January 2010.
The wettest day itself was the 7th, with 27.8 mm, but over 25 mm fell on two more days, namely the 10th [26.6mm] and 17th [25.1mm]. There were also 5 more days with over 13 mm of rain.
Even though 2011 was the wettest of the last three Januaries and had the highest daily total for a January day in those three years, it also had the highest number of dry days of the last three Januaries, with 12, of which 10 were after the 18th.

* = Since at least 2003