Downpours of torrential rain are expected to hit Chester , Ellesmere Port and surrounding areas from this afternoon well into tonight.
Strong winds and frequent lightning have been predicted by the Met Office, which has issued a weather warning for the region from 2pm until 11pm.
Forecasters say this could cause flash flooding and disruption to travel.
The Met Office has said: "A very warm and humid air mass is in place across much of the UK, with conditions marginal for thunderstorm development this afternoon as temperatures rise.
"Northern England and southeast Scotland are currently judged the most likely area to see scattered thundery downpours but even here many places will have no more than light rain.
"However, where storms do form, there is a lot of moisture and energy available, with the risk of more than 30 mm of rain in around an hour, large hail and frequent lightning."
