By Philip Eden

The weather was hot and humid until the 8th, warm and humid from the 9th-18th, then rather cool. Thunderstorms and torrential downpours occurred widely and frequently, and culminated on the 16th in the destructive flash flood which hit Boscastle in north Cornwall. As a consequence it was an exceptionally wet August. Sunshine was surprisingly plentiful, except in central and southeastern Scotland and in northeastern England where it was a dull month.

The extended warm spell with some remarkably warm nights was only partly offset by the cool weather during the last ten days or so. As a consequence the Central England Temperature (CET) of 17.7�C was 1.5 degC above the average for the standard reference period 1971-2000, and there have been only 11 warmer in Augusts in the 345-year long CET record. (However, four of those have come in the last 15 years).

The months highest temperature (recorded under standard conditions) of 31.5�C occurred at Northolt, northwest London, on the 8th. (Maxima recorded at rooftop sites are excluded from this analysis as they are non-standard). Afternoon temperature exceeded 21�C at several sites in London and the Southeast daily from July 13 to August 27, a total of 46 consecutive days). The night of 8th/9th was exceptionally warm with minima widely between 19 and 21�C. At Marham, Norfolk, the local minimum was 21.6�C, setting a new record for the station. It became markedly cooler in northern Britain from the 20th onwards, and in southern districts from the 21st. The maximum on the 20th at Wilsden, near Bradford, West Yorks, was just 12.7�C.

Rainfall averaged over England and Wales, was 157mm which is just over twice the average (218%, to be precise) of the standard reference period 1971-2000, making it the wettest August since 1956. It was, however, a long way short of the record of 193mm established in 1912. At Otterham, on the moors above Boscastle, 200.2mm of rain fell on the 16th, nearly all of it in a four-hour period during the afternoon. At the peak of the storm an estimated 88mm fell in just one hour. Such totals are rare in the UK, but not unprecedented. There was a wide geographical variation in monthly rainfall totals, from 318mm at Shap in Cumbria to just 39mm at Peterhead in Aberdeenshire.

Sunshine over England and Wales totalled 182 hours during August 2004 which is just one per cent below the 1971-2000 average. Totals ranged from 96 hours at Boulmer, near Alnwick, in Northumberland, where it was the dullest August since records began in 1945, to 225 hours at Hastings in Sussex.

(c) Philip Eden