A yellow weather warning is in place covering the whole of the South West following the heatwave.
The Met Office issued a yellow weather warning for thunderstorms last week which has now come into force.
It will remain in place until Wednesday 17 August.
The Met Office said: "Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services.
"Spray and sudden flooding could lead to difficult driving conditions and some road closures.
"There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost."
The yellow weather warning covers the whole of the South West today and tomorrow (15 and 16 August).
On Wednesday, it includes most of the region although parts of Gloucestershire are just outside of the yellow weather warning zone.
There are also three flood alerts in place in the region:
Hartland Point to Lynmouth
The Met Office says there is a 'small chance' homes and businesses could be flooded quickly.