A FOUR-DAY “extreme heat” warning has come into force with temperatures poised to exceed 35C.

The amber warning, issued by the Met Office, covers much of southern England including Sussex, with a threat of possible impacts to health, transport and infrastructure.

The alert came into force on Thursday and will last until the end of the week.

Temperatures are expected to peak at 35C on Friday in some parts of the UK, and may hit 36C in some places on Saturday.

The amber warning is the Met Office’s second-most severe after red.

Met Office deputy chief meteorologist Dan Rudman said: “Thanks to persistent high pressure over the UK, temperatures will be rising day-on-day through this week and an extreme heat warning has been issued. 

“Temperatures are expected to peak at 35C on Friday and Saturday, or even an isolated 36C on Saturday. Elsewhere will see temperatures widely into the high 20s and low 30s. 

“Coupled with the high daytime temperatures there will be some warm nights, with temperatures expected not to drop below the low 20s for some areas in the south.”

In Brighton and Hove, temperatures are expected to reach 30C on Thursday, before rising to 31C on Friday.

Friday will be a “fine and dry day with long sunny spells”, according to the Met Office. It’ll be hot for most, but cooler near eastern coasts.

From Saturday to Monday, there will be dry settled weather, with hot temperatures. Overnight mist patches are possible, before heavy thundery showers may begin to develop on Sunday night into Monday.

The extreme heat warning follows the driest July for England since 1935, when temperatures rose above 40C for the first time.

During July's heatwave, Britain faced power outages, damage to airport runways and rail tracks and dozens of fires, where the fire brigade faced its busiest week since World War Two.

Britain's environment minister George Eustice on Wednesday urged water companies to take precautions to protect water supplies and tackle the effects of the prolonged dry weather.