The Met Office has issued a yellow weather warning for thunder, lightning and flash-flooding.
The warning runs from 6am on Monday (August 15) until 11.59pm on the same day.
It comes as the Met Office has forecast three days of 'extreme heat' in the region with an amber heat warning in place until 11.59pm on Sunday (August 14).
Weymouth recorded its hottest day of the year yesterday with temperatures hitting 31°C - flash flooding often follows after periods of extreme heat.
A spokesperson for the Met Office said: "While some places stay dry, thunderstorms are likely to develop during Monday, bringing locally heavy rain and possible disruption.
"Very locally 20-30 mm of rain is possible in an hour, and up to around 50 mm in three to six hours.
"Hail and frequent lightning are also possible."
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