After a somewhat unsettled and very mild December, January 2019 was a little different with more of a settled pattern for much of the month and gradually becoming colder following a mild start generally bar a milder interlude around the 24th to 26th.
High pressure from the end of December continued into the start of January resulting in largely anticyclonic weather. Usually, such a setup would deliver relatively cold conditions with frost at night. However, this was a cloudy high limiting the potential for cool weather and it was generally mild. This continued for the vast majority of the first half of January. A northerly regime started to take hold on the 16th ushering in a colder spell of weather. With the exception of some mild weather on the 24th to 26th, the second half of January was colder than average.
The UK mean temperature for January 2019 was 3.7°C which is equal to the 1981-2010 average. The average overall monthly temperature was largely down to the fact that both halves of the month offset one another with the first half on the mild side and the second half on the cold side. Greatest deviations above average were over Northern Ireland where it was the mildest January since 2016 but most others didn’t have significant deviations from average.
In terms of the Central England Temperature (CET) series which has monthly mean temperatures back to January 1659, January 2019 came out with a mean temperature of 4.0°C, slightly below average for the 1981-2010 average but slightly above average for 1961-90. This was the exact same CET as January 2017.
The maximum temperature seen during January 2019 was 14.2°C at Slapton, Devon on the 25th but this was not as high as January 2018’s monthly absolute maximum temperature of 15.1°C. Meanwhile, the minimum temperature for the UK in January 2019 was -14.3°C at Braemar, Aberdeenshire on the 31st making it the coldest night in the UK since February 2012 and the coldest of this Winter up to that point – although the first few days of February 2019 bet the minimum from January but it remains the coldest night since February 2012.
As a good part of January was influenced by high pressure especially in the first half, it’s no surprise that January 2019 was a very dry month for the UK. In fact, with only 52% of the average rainfall, it was the 9th driest January on record for the UK back to the 1910.
Clackmannanshire, Scotland with 23.1mm of rain (15% of the average) had its driest January on record back to 1910. Other exceptionally dry places in Scotland through January 2019 include East Lothian with 9.9mm of rain (15% of the average) and Fife with 12.1mm (15% of the average). Southeast Scotland was the driest region compared to normal in January whilst northern Scotland was the wettest but even here, rather close to average than anything significant.
East and North East England had just 22.9mm of rain during January 2019 making it the second driest January on record here back to 1910 with only January 1997 drier at 15.0mm.
It was the 7th driest January on record for England back to 1910 (driest since 2006) with them recording 45% of the average January rainfall.
The period May 2018 to January 2019 was the driest such period for England since 1996-97 with 533.6mm of rain compared to 473.0mm in 1996-97. The driest since 1996-97 besides 2018-19 was actually very recent with 2016-17 at 546.2mm.
500mb height anomaly reanalysis for January 2019 from NCEP/NCAR show why the month was dry and anticyclonic for the UK. There was a large area of above average heights through the Atlantic and ridging into the UK with below average heights to the east of Europe resulting in some record breaking snowfalls there. Meanwhile, the UK had a benign month in comparison being on the periphery of a potent northerly flow for the vast majority of the time.
January 2019 featured a similar distribution of sunshine to December 2018 with northeastern regions tending to be favoured and the west mainly dull in nature. Parts of southern Scotland had their sunniest January since 2000 whilst others especially to the east had a sunnier January in 2017. Nevertheless, the whole of Scotland had its 10th sunniest January on record back to 1929.
In contrast, the southwest and parts of the west including Northern Ireland, western Wales and southwest England had quite a dull January. At Camborne, Cornwall, it was the dullest January on record back to 1961 with only 28 hours of sunshine.
For this month’s featured photography, we’re sharing some pics from snow events in the second half of January.