For the 6th successive September, average daytime temperatures of 14.7°C in the UK were above the 1961-1990 long-term average of 13.6°C. This indian summer warmth was quite uniform across the country, perhaps a little more in the south and west and a little less in the north and east. Over the last 100 years there have been only 9 warmer Septembers and three recording equal temperatures. Interestingly Birmingham was colder than normal. The only coolish spell during the month was from 18-20th September when temperatures were 1-2C below usual. Guernsey was warmest with an average of 20.3deg;C and Lerwick coldest with 12.6deg;C.

After a modestly dry summer, September 2000 was extremely wet. Total rainfall in England and Wales was 132.6 mm, which makes it the wettest September since 1981 (139.9mm). There had only been eight wetter Septembers over the past 100 years. Until the end of August, there had only been 15 days this year recording a nationwide average of 6mm or more rainfall; in September, there were 10 further such days.

Heavy rain on the 10/11th caused significant transport disruption in western Scotland and Northern Ireland. In southern England, a slow-moving frontal system, with embedded thunder cells, produced some remarkable falls on the 14/15th, e.g. Penzance, 62 mm in 11 hours, Portsmouth, 60 mm in around 3 hours, 82 mm in a day at Walderton in West Sussex, and 69.4 mm in 12.5 hours in west London.

Large areas of the Midlands and the East reported >20 mm on the 19th and the 28/29th was also very wet (in NI almost 70 mm was recorded at Helen's Bay, near Bangor). Apart from a few localities (e.g. the eastern tip of Kent) rainfall totals for September exceeded the average throughout E&W and large parts of the North-East reported >200%. Southern Scotland was wet also but the north was notably dry (in parts of Skye only around 50%). England and wales recorded its third successive wet September. Wettest was Eskdalemuir with a total of 192 mm. Driest was Guernsey.

Not surprisingly for such a wet month, September was quite cloudy, although parts of Scotland enjoyed above average sunshine. Much of England and Wales recorded about 80% of usual sunshine, Birmingham only 70%. The 13-15th was the gloomiest 3-day spell in Britain since early February. Sunniest was Folkestone with a total of 162 hours of sun. Dullest Eskdalemuir with only 81 hours of sun.