Days of thunder
1 August 2011
The summer thunder map shows the average number of days in summer (June to August) when thunder is heard across the UK.
Thunderstorms are most frequent in the summer, with the warmer areas of eastern England most prone. The image is from The Met Office Book of the British Weather. A selection of maps from the book show the seasonal variation in the number of days when thunder can be heard. Timing the gap between seeing a lightning strike and hearing thunder can help to estimate how far away a storm is, with every five seconds representing a mile. Thunder is often heard up to about 10 miles away and occasionally as far as 20 miles.