Britain will be smashed by seven days of heavy rain from today with thunderstorms set to batter the UK.

Brits yesterday basked in a 20C mini-heatwave – but this week will see torrential downpours and possible flooding. The weather charts show up to 57mm of rain will fall between Monday and Sunday this week.

Monday will see a mixture of sunshine and showers, to get the working week underway.

The Met Office said in a Twitter message: A mix of pleasantly warm #sunshine and showers to start the new week.”

The Met Office’s outlook for Monday to Wednesday says: Generally unsettled with a mixture of sunny spells and showers, as well as some more prolonged periods of rain.Some heavy bursts likely at times with a risk of thunderstorms.

The Met Office’s long range forecast from May 13 to May 22 says: “Cloudy on Thursday starting with outbreaks of rain and showers, especially in the southwest of the UK.

The showers are expected to become more widespread during the day, with these heavy and potentially thundery for the south. The breeziest conditions expected in the far northwest.

The unsettled theme then continues through the remainder of this period, with longer spells of rain and showers in between, the clearest conditions are most likely in the north.

It’s likely to be breezy at times; especially around coastal areas, where gales may occur. Temperatures will be near to or slightly below average, though with the formation of overnight frosts becoming unlikely.

Saturday saw torrential rain and gales across the country as a week’s worth of rain fell in 24 hours in some areas. Brecon Beacons in South Wales saw 125 mm of rain as the UK stuttered towards summer.