Although the weather became much less settled during the second half of the month, September turned out to be warmer, drier, and sunnier than average over most parts of the UK. Even during the last two weeks, temperatures continued above the seasonal norm, albeit by only a small margin, while there was plenty of sunshine between the bouts of rain. Largely thanks to the early heatwave, September turned out to be the warmest since 1999, and the fifth warmest in the last 100 years � only 1929, 1949, 1961 and 1999 were warmer. The Central England Temperature, which takes into account both daytime and night-time readings, finished up at 16.1°C, some 1.4 degC above the average for the standard reference period 1971-2000. Temperature-wise, the first half of the month was second only to 1949.

The highest individual temperature was 29.7°C recorded at Northolt aerodrome, northwest London, on the 4th, making this the hottest September day anywhere in the UK for six years. In Scotland, Charterhall in Berwickshire recorded 27.4°C on the same day, and this was the highest Scottish reading in September since 1991. The preceding night had been exceptionally warm and muggy with the temperature remaining above 18°C all night over the southern half of Britain, and at Guernsey airport the minimum reading was 20.4°C. The only other instance of such high night-time temperatures this late in the season occurred in 1949.

Much colder weather moved into Scotland during the second week, and some remarkable temperatures were recorded on the morning of the 9th, including �3.5°C at Kinbrace and �2.6°C at Altnaharra (both in Sutherland). We have to go back to 1986 to find similarly sharp night frosts this early in the autumn. After mid-month occasional cold nights brought local air frost and widespread ground frost even to southern districts.

In spite of the frequent rain during the last week, September�s aggregate rainfall was below normal except in northern Scotland, northeast England and parts of East Anglia. Averaged over England and Wales, the month�s aggregate was 71mm, roughly 15 per cent below the long term average. The equivalent figure for Scotland was 21 per cent below, and for Northern Ireland 17 per cent below. Aboyne in Aberdeenshire was the driest place in the UK with a monthly total of just 18mm.

Sunshine duration was slightly below average in the north and west of Scotland and in Northern Ireland, but well above average elsewhere � by as much as 30 per cent in Herefordshire. Monthly totals approached 200 hours in Norfolk, the Channel Islands, and the southwest Midlands.

© Philip Eden