The warning was issued by the Met Office on Tuesday 7 September.
The warning is for between 11 am and 8 pm on Thursday 9 September.
The warning reads:
Following overnight rain and showers, more intense showers and thunderstorms are expected to break out fairly widely from late-morning, before easing during the evening.
Whilst most areas will miss the most intense storms, torrential downpours are possible in a few places.
Where these occur, there is potential for 20 to 30 mm of rain in less than an hour and up to 40 mm in 2 hours.
This would have the potential to generate surface water flooding, especially if it falls over an urban area.
