The tornado seen in Wales began as a waterspout

About an inch (25mm) of rain, driven by winds gusting up to 80mph, could lead to water surging over low-lying land, forecasters warn.

Heavier rain is due in the hills and snow is likely over the Peak District Welsh mountains and southern Pennines.

The Met Office has warned the stormy conditions "could cause structural damage and localised flooding".

The stormy weather is expected to hit the south-west coast of England at about 0600 GMT.

On Sunday evening, the Environment Agency had 26 flood watch warnings in place, including 15 in the South West, four in the Thames region and three in Wales.

Areas affected in the South West include much of the Dorset coast and many west Dorset towns, including Charmouth, Bridport, Beaminster and Burton Bradstock.

The agency says flooding may also occur from the Hampshire/ Wiltshire border village of Plaitford, west of Romsey, to Testwood, near Southampton.

Parts of southern Wiltshire are also at risk.

Gales and rain are expected to spread eastwards during Monday, possibly reaching south-east England by the afternoon.

Tornado

Forecasters say similar stormy conditions are also possible late on Tuesday.

But the Met Office warned the most damaging winds may occur in countries such as Holland, Belgium and northern Germany, which could experience gusts of up to 90 or 100mph later on Monday and into Tuesday.

With heavy rain and winds already battering the south Wales coast, eyewitnesses reported seeing a tornado measuring 2000 feet on Sunday.

Onlookers said the sky went dark and the sea level rose as it made its way up the Bristol Channel before sweeping inland.

It did not cause any damage and died out after 20 minutes.

A Met Office spokesman said such phenomena were "far from unusual", with between 50 and 100 tornadoes and waterspouts in and around the UK each year.