Winter 2018-19 has gotten off to a mild start with December. Rainfall and sunshine were more variable however.

Temperatures

December 2018 was a very mild month with a UK mean temperature of 5.8°C which comes to +1.9°C above the 1981-2010 average but despite this significant deviation, it was 0.1°C cooler than December 2016 and just over 2.0°C cooler than the phenomenally mild December of 2015. As a result, December 2018 only comes out as the joint 8th mildest on record back to 1910. In terms of mean minimum temperatures, December 2018 came out as much as +3.0°C above the 1981-2010 average in the southwest quarter of the country and for Wales, it was the joint 6th mildest on record for mean minimum temperatures. All these records refer back to 1910.

In terms of the Central England Temperature (CET) series which has monthly mean temperatures back to January 1659, December 2018 came out with a mean temperature of 6.9°C making it the mildest in the series since 2015 which was well above that of December 2018 with a value of 9.7°C. It was the joint 9th mildest on record back to 1659.

Kew Gardens, London recorded the maximum temperature of the month with 15.9°C on the 2nd December which was only the highest December temperature since 2016. Braemar, Aberdeenshire recorded the minimum temperature for December with -8.8°C on the 5th which was not as low as December 2017’s minimum of -13.0°C at Dalwhinnie, Highland and Shawbury, Shropshire on the 11th and 12th respectively. This minimum was just barely lower than October 2018’s minimum of -8.6°C.


UK mean temperature anomaly map (against 1981-2010 averages) for December 2018.
Credit: UK Met Office.

Rainfall

December was another mixed month in terms of rainfall distribution around the UK. The wettest conditions tended to be the south of the country with an overall 99% of average rainfall. This was the wettest December since 2012 over some parts of England but it was generally on a par with or relatively drier than December 2017 and much drier than December 2015 in the north.

December 2018 was not very remarkable overall in terms of rainfall for the UK as the decade has had wetter (including 2015 and 2017) and drier Decembers (including 2010 and 2016) than it.


UK rainfall anomaly map (against 1981-2010 averages) for December 2018.
Credit: UK Met Office.

Sunshine

Sunshine was very divided during December 2018 with eastern parts of the country tending to be on the sunnier side but the west was dull and in some parts, exceptionally so with less than half the normal amount of sunshine in an average December.

With a total of 22.6 hrs, it was the third dullest December on record in Northern Ireland back to 1929 behind only 1931 (18.1 hrs) and 1977 (18.7 hrs). In contrast, eastern Scotland recorded a total of 45.7 hrs of sunshine during December 2018 making it the joint sixth sunniest on record in the region. In the southwest England/south Wales series, it was actually the dullest December on record back to 1929 with a total of only 22.7 hrs of sunshine which also made it the dullest month on record in these regions. January 1996 was the previous dullest month on record here with 25.6 hrs of sunshine.


UK sunshine anomaly map (against 1981-2010 averages) for December 2018.
Credit: UK Met Office.

In spite of such a dull December for some parts of the UK, 2018 finished as the second sunniest year on record for the country back to 1929 with a sunshine total of 1580.7 hrs only beaten by 2003 with 1586.8 hrs. In East Anglia, it was actually the sunniest year on record back to 1929 with a sunshine total of 1872.9 hrs beating its previous record of 1865.0 hrs in 2003.

February, May, June, July and October all fell within the top 5 sunniest for their respective months in the UK series back to 1929. May was the sunniest on record.

Annual UK sunshine totals from 1929 to 2018.
Credit: UK Met Office.

Featured photography

For this month’s featured photography, we’re going to share some pictures from tweeters on the freezing rain event that was caused by Storm Deirdre on 15th December 2018 and some over the Christmas period too. This was the second of two notable freezing rain events during 2018 in the UK; the other for interest was during Storm Emma on March 2nd/3rd.

I hope you have enjoyed this latest stats article and thank you for sending in your pictures. See you next month in the January 2019 stats article!

Sean Bruen is a forecaster for Metcast (and Snow Watch). His main interests are historical and long range weather. He LOVES snow (his Twitter account is @SnowbieWx, go figure!) and his favourite season is Winter.

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