The weather in September

http://www.theguardian.com/uk-news/2015/oct/04/september-rainfall-temperatures-sunshine-winds

Version 0 of 1.

September’s weather was quite different to previous months, being dry and fine in the north-west and less settled at times in the south-east of the UK. The eastward movement of low pressure systems was blocked in the first and last weeks by areas of high pressure that gave mostly fine, settled weather with chilly nights. The middle of the month was more unsettled but unlike recent months, the jet stream pushed well to the south allowing low pressure systems to affect mostly southern and central Britain. This gave northern districts a dry month and it was notably cool in all areas.

Daytime Temperatures

The average daily Central England Temperature was only 12.6C, 1.4C below the average for 1981-2010 but just 0.7C below the average for the whole series from 1659. The coolness was due to a lack of mild south-west airflows and a high frequency of clear nights. Remarkably, the highest day temperature and the lowest night temperatures occurred in the same place and on the same day – at Braemar on the last day of the month when the temperature climbed from a low of -1.3C at dawn to reach a high of 24C.

Rainfall

Rainfall over England and Wales averaged 57mm, which is 73% of the average for 1981-2010. Northern parts of the UK were drier; Northern Ireland averaged 33mm, 36% of average and Scotland averaged 37mm which is just 32% of average. The month was particularly dry in the first and last weeks when high pressure dominated. The infrequency of west and south-west winds meant that north-western upland areas were driest. At Loftus (Redcar & Cleveland), 53mm of rain fell in the 24 hours to 6pm on 15 September.

Sunshine

September was mostly quite sunny with a large number of nearly cloudless days under the high pressure systems early and late in the month. With rather frequent easterly winds, areas near North Sea coasts were cloudier. Western areas were sunniest with Cardiff and Bournemouth both reaching 200 hours for the month and Glasgow reaching 158 hours. The largest local excess above average was 143% at Anglesey.

Winds

Winds were light for most of the month. Winds gusted to over 60mph on 11 days over the highest mountains in Scotland, peaking at 100mph on Cairngorm summit on 12 September. Gusts approached 70mph on the 14th on the coast of Carmarthenshire and on the Isle of Wight as a depression crossed the UK.

Rick Birch MeteoGroup