July 1955 was a very warm, dry and sunny month. Large areas of south-east England had very little rain, while Bury St Edmunds in Suffolk did not see a single drop.
And yet in any table of Met Office UK weather records, one figure stands out: the wettest day – or to be precise, the heaviest rainfall recorded during a 24-hour period (9am-9am). It happened in the village of Martinstown – also known as Winterborne St Martin – in the Dorset countryside three miles (5km) south-west of the county town of Dorchester (Thomas Hardy’s Casterbridge).
On 18 July 1955, 27.9cm (11 inches) of rain fell, mostly during a period of about nine hours from mid-afternoon to midnight. That is the equivalent of three or four months’ rain – a rate roughly 200 times greater than usual.
Martinstown was not the only place that had heavy rainfall: so did neighbouring areas, right down to the coast at Weymouth, where the nature reserve at Radipole, close to the town centre, overflowed with water.
The record rainfall was the result of very hot weather that preceded it, which built up humidity in the air and led to what were described as apocalyptic thunderstorms. Fortunately, the chalky soil of the area absorbed much of the rain, though floods did occur.
The Environment Agency measured 314mm (over 12 inches) at Seathwaite in Cumbria on 19 November 2009. But the Met Office still awards the record to Martinstown.