UK weather: Atlantic jet stream set to end record-breaking heatwave in just 36 hours

Northern and northwestern regions will be the first to cool before the whole country settles by Sunday.

A northwest-southeast split will bring highs in the 30Cs to London, the Home Counties and Channel coasts on Saturday, with Scotland dipping into the bearable teens.

Met Office meteorologist Aidan McGivern said: “A big change is on the way, and by Sunday, the jet stream is firmly back in control, sending low-pressure systems in from the Atlantic with a return to changeable but cooler weather into next week.

“Friday is a largely sunny and breezy day towards the southwest, and temperatures are starting to come down, but they are going to stay elevated towards central and eastern parts of England.

“It will be cooler for Scotland and northern Ireland, and as we go into Saturday, it is a warm start to the day to eastern and southeastern parts of the country, although it is feeling fresher further west, but in the east, it is still a very hot day.

“Sunday is the day that cooler and more changeable weather spreads to all parts, and it will be a fine summer’s day even though we have lost the heat and humidity.”

Meanwhile, Britons will have to sweat through another 24 hours of stifling heat, particularly in the southeast, where sky-high humidity will continue to bubble the mercury.

Cool winds crashing into hot air will spark spectacular thunderstorms as experts warn of a possible repeat of Monday night’s midnight fireworks.

Mr McGivern said: “High humidity could spark some really lively thunderstorms down to the south and the southwest with frequent lightning, torrential rainfall and very gusty winds, 60mph to 65mph gusts.

“We are going to see a significant change in temperatures as these storms move.

“On Monday it will feel cooler and much more comfortable, and that is because the jet stream is back in charge of the weather.

“It is swinging across the Atlantic, and it has more oomph to it over the mid-Atlantic, picking up an area of low pressure, and we have more lows lined up to come in next week.”

Met Office heatwave warnings across the south remain in force into Saturday.

A separate thunderstorm warning is in place across northern and western regions this morning and Scotland until midnight.

A Met Office spokesman said: “Spells of heavy rain and thunderstorms initially over northwest Scotland are likely to become more widespread during Friday morning.

“Further thunderstorms and spells of heavy rain are possible in the afternoon before becoming confined to more northern areas of Scotland later in the day.”

Jim Dale, meteorologist for British Weather Services and co-author of Surviving Extreme Weather, added: “The heat will come to an end this weekend for all of the country.

“With the high humidity, though, there will be a risk of some very lively thunderstorms.”