The Met Office is warning people to be prepared for thundery showers on Tuesday and Wednesday, and has issued a yellow weather alert.
The Met Office's chief forecaster said: 'Some places will miss them altogether but where they do occur, there is the potential for locally 20 to 30 mm of rain within an hour.
Forecasters are also warning of some localised flooding of homes, businesses and roads.
Oli Claydon, a Met Office spokesman, said some areas would see between 20mm and 30mm of rainfall in an hour.
Tonight a band of heavy thundery showers is expected to push northwards with a risk of hail.More news: Price Target Analysis General Motors Company (GM)
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He added: "There will be scattered storms and some areas could see 30mm of rainfall in an hour, while there could be rainfall of up to 50mm in two to three hours in some areas".
Wrexham is now basking in glorious sunshine and enjoying another spell of summery weather - however that could be set to change looking at a current weather warning for the middle of the week.
After all the recent talk of a heatwave, Cornwall is braced for thunderstorms, lightning and torrential downpours.
The good news is that the thunderstorms will clear through the morning, making way for bright spells across the area.
"Large hail may be an additional hazard on Wednesday afternoon".