The Met Office yellow ‘be aware’ warning is valid between 9am on Tuesday and 6am on Wednesday.
A Met Office spokesperson said: “Heavy showers and thunderstorms are expected to develop during Tuesday across much of Wales, northern and central England.
“These will last well into the night across north Wales and north-west England in particular where they could be prolonged in places.
“20 to 30mm of rain is possible in around one or two hours and a few places could see around 60mm in three to six hours.
“Lightning and hail may pose additional hazards in a few locations.”
What to expect, according to the Met Office
- Spray and sudden flooding could lead to difficult driving conditions and possibly road closures
- Where flooding or lightning strikes occur, there is a chance of delays and cancellations to train and bus services
- There is a small chance that homes and businesses could be flooded quickly, with damage to buildings from floodwater or lightning strikes