Forecasters have predicted heavy rain in Oxfordshire - with the potential for severe flash-flooding.
The Met Office said there was a 60 per cent chance of severe or extreme weather hitting the county, which could lead to incidents of flooding after several days of above average rainfall. Motorists were advised to take care.
A Met Office spokesman said: "Rain will be heavy at times with the potential for 25 to 35mm to fall widely and up to 50mm in places."
Tonight, the Environment Agency had not put any rivers in the Thames Valley on alert, but that is likely to change.
Barry Russell, the agency's area flood risk manager, said: "It's fair to say we do have some concerns. We are expecting 30 to 38mm of rainfall, but over about 18 hours.
"The ground can cope fairly well at the moment, although there may be some surface water issues."
Nationally, the worst of the weather is expected in Cornwall and Devon, where up to 75mm of rain is due to fall.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article