High summer temperatures will finally hit the UK next week when it will be hotter than Barcelona, forecasters have said.  

But this weekend flood warnings, persistent rain and thundery spells are continuing to plague parts of the country.

“Conditions, overall, remain fairly changeable,” said Simon Partridge, a meteorologist at the Met Office. “Saturday’s outbreaks of rain will clear up by nightfall, though we are expecting some rain to continue in northeast England and Scotland.”

Overnight temperatures on Saturday will be in the mid to high single figures, he added, sinking to 1C in northern regions.

Sunny spells and rain will mingle, with heavy showers on Sunday, when thicker cloud is forecast across northern Scotland.

Prolonged rainfall is also expected across the southwest and Wales.

“Wales will start dry on Sunday, with the rain getting heavier as the day goes on,” Mr Partridge said. “The main thing, across the UK, is that Sunday will be a lot windier. Very breezy.”

Temperatures will improve slightly, rising to 21C in the southeast and 17C across the rest of the UK.

Mr Partridge said the conditions were slightly below usual summer temperatures.

“We’re a few degrees below where we should be,” he said. “It should be around 22C in the southeast and 19C or 20C elsewhere.”

Monday is expected to be mostly dry, though persistent rain will continue in the southwest.

But temperatures are set to surge later in the week as an area of low pressure moves into the UK, with parts of the country set to be as warm as Barcelona and Rio de Janeiro.

“Tuesday and Wednesday will bring a bit of a change,” Mr Partridge said. “It could get very warm – we could see 26C in the south.”

The low pressure system will spread to northern regions, with temperatures in Northern Ireland and Scotland expected to hit 18C.

But forecasters also expect the system to bring heavy rain and thundery showers, which will move from the south of the UK to other regions. 

“It is uncertain at the moment but we are keeping an eye on Lincolnshire where a river has burst its banks,” Mr Partridge said. “We may issue some rainfall warnings at some point next week – that’s the main thing for the public to keep an eye out for.”

The Environment Agency (EA) has issued 16 flood warnings and 37 flood alerts, mainly in the midlands and northeastern regions.

The Royal Air Force dropped 270 bags of material to fill a breach in the River Steeping in Wainfleet on Friday, after the Lincolnshire town received more than two months’ of rain in just two days.

An EA spokesperson said it was working with emergency services in the area over the weekend on measures to tackle the flooding.

Additional reporting by agencies