AS much as a month's average rainfall could soak most of the country over two days as forecasters warn of possible flooding.

MeteoGroup said rainfall totals in England and Wales are expected to be between 40 to 50mm from Thursday to Friday, with the risk of intense thundery downpours, but could be high as 70mm in places.

The picture in the North-East and North Yorkshire is expected to be equally bad with "significant" rain expected on Friday in particular.

A spokesman for MeteoGroup said: "The rain will start coming on Thursday afternoon, showery in nature, but will then set in more through the overnight period.

"This will turn heavy with the chance of the odd thunderstorm. The rain through Friday daytime could be quite persistent and torrential at times.

"There could quite widely be 40 to 50mm, maybe up to 70mm in places by the end of Friday. The average precipitation in Newcastle for the whole month of August is typically 60 to 70mm."

The rain is being blamed on a thundery area of low pressure which is developing over northern Spain and which will spread warm, humid air northwards over the next two days.

Temperatures on Friday will reach 16-18C, but it will feel humid. Saturday is expected to be brighter, but with the odd shower remaining and similar temperatures, albeit feeling fresher.

The Met Office has issued a severe weather warning for all of England and Wales on Friday.

A spokesman warned: "As we have already seen this summer, this type of weather situation has the potential to cause sudden, localised surface water flooding and hazardous travelling conditions."

The AA issued advice for motorists who may be caught in flash floods.

Paul Watters, head of roads policy, said: "Flash-flooding in the summer can be hit-and-miss but potentially dangerous for anyone caught up in it. The AA advises drivers to keep an ear out for local weather warnings and traffic news, and be prepared to encounter flooding.

"Flooding close to where you live may present less of a problem as most drivers know which are the hazardous stretches of road and can avoid them. Those on holiday face a more precarious challenge and asking local people where they might run into flooding is a wise move."

The AA warns motorists only to drive through water if they know it is not too deep - generally this would mean no more than halfway up the wheels. Also they should not try driving through fast-moving water, such as in a ford - the car could easily be swept away.