Parts of Britain are set to be battered by the worst storm of the year so far, forecasters warned today, with heavy rain and gale-force winds bringing a risk of flooding and damage from falling trees.

The Met Office has issued severe weather warnings for Wales and the south of England, predicting 40 millimetres of rain in southern and western parts of England and Wales on Friday, with as much as 75 millimetres on higher ground. This will be followed by more heavy rain and severe gale-force winds on Saturday, it said, with gusts of up to 80 miles per hour expected.

"For England it is probably likely to be the strongest winds this year," said a Met Office spokesman.

"It is not a surprise to see it," he added. "It is certainly a feature of weather at this time of year but 80 mph is certainly getting in to the realms of winds where you are likely to see disruption due to structural damage, for instance trees coming down."

The Environment Agency warned the heavy rains could bring a risk of flooding, particularly across Wales and the south west of England, which could continue into next week, due to forecasts of further heavy rain on Monday.

"These bands of rain could cause problems and we would urge people who live in homes that are vulnerable to flooding to start thinking about taking precautions to protect their properties," said a spokesman.