Temperatures are expected to reach 35C this week as the UK prepares for what could be its longest heatwave in 50 years. The heatwave is set to last longer than expected, with Thursday and Friday forecast to bring the hottest conditions of the current spell. Some areas could even reach highs of 35C to 36C as high pressure keeps skies clear, conditions dry and sunshine widespread.

Amber and yellow heat health alerts have been issued by the UK Health Security Agency (UKHSA), meaning significant impacts are likely across health and social care services due to the high temperatures. This heatwave could be one of the longest the UK has seen since 1976. According to the Met Office, the prolonged spell of hot weather will continue into next week. The forecaster added: "While the heat will gradually ease across southern and eastern parts of the UK during the weekend and into next week, very warm weather is set to continue as the focus of the highest temperatures shifts towards the southwest."

Deputy Chief Forecaster Tom Crabtree said: “Many people will understandably want to know how long the current heatwave is likely to last. While temperatures are expected to ease across southeast England through the weekend and into next week, it won't be a straightforward end to the warm weather.

“High pressure is expected to remain in charge through much of next week, but it will gradually migrate northwards. This means that an easterly wind will become established in the south, and the focus for the hottest conditions will migrate towards the southwest.

“As a result, some places that have seen the highest temperatures during recent weeks will begin to cool. It will however, remain very warm – especially in the southwest – and heatwave thresholds may continue to be met in places.

“The overall signal is for continued fine, dry and very warm weather at times for many parts of the UK into next week. There is however a chance of thunderstorms spreading into parts of the south and southwest.”

A National Fire Chiefs Council (NFCC) spokesperson also said: "When the weather stays hot and dry, it only takes one spark to start a wildfire. What can begin as a small fire can spread incredibly quickly, putting people, homes, wildlife and our countryside at risk.

"We’re asking everyone to take extra care outdoors, whether that’s avoiding disposable barbecues in the countryside, parks or moorlands, or making sure cigarettes are fully extinguished. A few simple actions can make a huge difference and help prevent fires before they start."

The heat will remain intense into the weekend, particularly in the southwest of England, where temperatures could reach 34C on Saturday and around 33C on Sunday before a slow decline begins.

Further north, Scotland and Northern Ireland will also experience unusually warm conditions, with temperatures possibly reaching 27C to 28C on Friday and staying in the mid-20s Celsius over the weekend.