The Met Office says nearly 20 Cornish towns are expected to get rain on Wednesday as downpours continue.
Last week was a scorcher, with the UK's fifth heatwave of the summer, but the south west has turned cooler and wetter this week. The region is expected to be drenched on Tuesday (August 18), with rain continuing on Wednesday (August 19).
The Met Office forecast for the UK on Wednesday is: "Rain will soon clear the far southeast, with sunny spells developing widely. Heavy, frequent showers across Scotland will spread more widely through the day, with some potentially turning thundery."
Weather maps show the high temperature in Cornwall will be 21C. They also show a deluge will hit the county.
A large band of rain will soak both Devon and Cornwall in the early hours of the day, followed by heavy patches of rain over St Ives just before dawn. Isolated showers will remain overhead until mid-morning.
From then, rain will largely stop in Cornwall, aside from the odd spot of precipitation around 1pm, until the evening. Showers then return, as some of the scattered clouds could bring heavier downpours.
The 18 Cornish towns set to see rain on Wednesday are:
Met Office Maps Forecast Wednesday Downpours for Nearly 20 Cornish Towns