By Philip Eden

Mainly cool weather between the 10th and 25th was outweighed by several warm days during the first week and a burst of exceptional heat right at the end of the month.

The Central England Temperature (CET) for May 2003 was 11.7deg;C, which is 0.4 degC above the mean for the standard reference period 1971-2000; it was, nevertheless, the coolest May since 1997. In the last 100 years 30 Mays were warmer as measured by the CET, three had the same mean temperature, and 67 were cooler. Daytime temperatures, averaged across the whole month, were within a degree of the long-term normal over much of the UK, but approached 2 degC above nomal in northeast England and East Anglia. Night-time temperatures were generally around 1 degree above average.

The hot spell at the end of the month was notable. The temperature reached 29°C at St Helier, Jersey, on the 30th, and 30°C in the Greater London area on the 31st - the highest in May here since 1953. By contrast, there were widespread frosts around mid-month, notably on the morning of the 16th when the temperature slumped to -4.3°C at Loch Glascarnoch in Wester Ross.

Rainfall, averaged over England and Wales, was 77mm which is 27 per cent above the average for the standard reference period 1971-2000, but it was not as wet as May 2002. During the last 100 years only 25 Mays were wetter while 75 were drier. In the main population centres in Scotland the total for May 2003 was 85mm which is 42 per cent above the normal amount, whereas the Northern Ireland total of 101mm was 74 per cent above. Torrential downpours accompanied severe thunderstorms and led to some flooding in Lanarkshire on the afternoon of the 30th. Monthly rainfall totals ranged from 25mm at St Catherine's Point on the Isle of Wight to 252mm at Capel Curig in Snowdonia. Percentages ranged from 54 at St Catherine's Point to 237 at Lochluichart in Wester Ross.

Sunshine over England and Wales totalled 198 hours during May 2003 which is just one per cent below the long-term average for the month. The equivalent figure for Scotland's main population centres was 150 hours (15 per cent below), and for Northern Ireland it was 142 hours (28 per cent below). Monthly aggregates ranged from 104 hours at Hillsborough in County Down to 268 hours at Clacton in Essex.

Philip Eden's new book, The Daily Telegraph Book of the Weather, published by Continuum, is available for £16.99 (post free in the UK). To order please call Telegraph Books Direct on 0870 155 7222 or visit the amazon.co.uk website.

(c) Philip Eden