Parts of Britain have been warned to expect a deluge this week which could see half a month's worth of rain fall in a single day.
Areas in the South West and Wales are likely to be worst affected with up to 25mm falling on Tuesday.
Some forecasters have warned that there is no end to the wet weather in sight as a band of rain sweeps across the country.
Temperatures will improve towards the end of the week rising to 15C (59F) or 16C (61F) in London on Thursday and Friday.
However, it is likely to remain wet with a combination of sunshine and showers.
Matt Dobson, a forecaster with MeteoGroup, said towards the end of May we would see a return to more "settled" weather.
He said: "There is some rain on the way. Tuesday is looking like the wettest day of the week for southern parts of the country.
"There will be lots of rain moving from Devon and Cornwall and the South West to Wales, with up to an inch or 25mm on Tuesday daytime.
"It's a lot for a day - a typical place in southern Britain would see around two inches of rain in a whole month. Places could see half a month's rain in a day."
But he said that predictions of a summer as wet as last year were premature.
"Time and time again it's been shown these kinds of long range forecasts don't work", he said.
"Looking forward though there are signs of slightly more settled weather towards the end of May. It's still developmental work trying to predict a few months ahead."