The Environment Agency has issued eight floods warnings in the south-west of England despite the region being affected by the worst drought since 1976.
Residents in the south-west have been advised to take "immediate action" to protect their property as heavy rain on dry ground could lead to flood.
The Agency say Rivers Coley, Upper and Lower Axe, Char, Upper and Lower Otter, Taw and Wriggle were likely to break their banks in a week of heavy rain.
Lower level flood alerts were also issued in 22 areas of southern England, with weather warnings in Wales.
The Met Office said: "The public should take extra care and be aware heavy rain may lead to localised surface water flooding and poor driving conditions."
"The rain will be accompanied by strong and gusty winds and, on higher hills and mountains, significant and heavy falls of snow will occur".
Around 40mm (1.6in) of rain is forecast on Wednesday, but showers are predicted across the whole of the country for the rest of the week.
Scotland is also expected to see heavy rain in the coming weeks
The warning comes as parts of England suffer its worst drought in a generation. The South West, South East, Anglian region, Midlands and parts of Yorkshire have recently been given official drought status, with a hosepipe ban still expected to be in place.
Experts warn that only prolonged periods of heavy rain will be able to replenish the ground water needed to end the drought.
Thames Water said: "It has taken two years to get into this drought and a couple of wet weeks won't get us out of it, though it is greatly appreciated.
"The rain will boost flows in the river temporarily but it will not soak into the earth and top up groundwater levels like winter rain.