UK weather: Thursday and Friday forecast to be hottest days of the year

Temperatures could reach 32C in south-east but thunderstorms are expected to bring torrential rain from Friday evening. Forecasters expect Thursday to be the hottest day of the year so far, with temperatures reaching 30C (86F), and Friday could be even hotter at 32C.


The Met Office issued an alert, saying there was a 60% chance of heatwave conditions in England between 8am on Friday and 8am on Sunday. But it also issued a severe weather warning for much of the UK on Saturday, when thunder and heavy showers are expected, with the potential for localised flooding.


Krista Mitchell, a Met Office meteorologist, said: "Things are certainly heating up today and again tomorrow. Much of the country can expect thunder from Friday into Saturday. We can expect some quite torrential showers over a large swath of the country."


The Met Office said the highest temperature of the year until now in the UK was 28.7C on 4 July. On Thursday highs of at least 30C are expected in the south-east. The heat is due to a "Spanish plume" sweeping across the south, which can lead to warm conditions and heavy showers or thunderstorms.


Forecasters said Sunday should bring fresher conditions but the south of the country is expected to remain warm into next week. Public Health England warned that the heatwave conditions could have a "significant effect on health". It said people should consider staying out of the sun during the hottest part of the day, drink plenty of fluids and wear suncream that is at least factor 15.


It has also asked people to be aware of children and the elderly, to ensure they are not suffering because of the heat. People should never be left in closed, parked cars, especially infants, young children or animals, a spokesman added. Pet owners were advised to keep their animals well hydrated.


"While many people enjoy hot weather, high temperatures can be dangerous, especially for people who may be particularly vulnerable such as older people, young children and those with serious illnesses," said Dr Paul Cosford, director for health protection at PHE.


"Everyone can enjoy the sun safely by keeping out of the heat at the hottest time of the day, avoiding sunburn and staying hydrated with plenty of cool drinks. Older people and those with long-term illnesses are particularly vulnerable to the effects of very hot weather, so it's important to look out for them and keep indoor areas as cool as possible."


The east Midlands, West Midlands, east of England, the south-east and London are the regions most likely to experience heatwave conditions, the Met Office said.


"There is a 60% probability of heatwave conditions between 8am on Friday and 8am on Sunday in parts of England," it said. "The highest temperatures are likely on Friday … then a very humid night to follow. Heavy thunderstorms in eastern areas on Saturday will lead to slightly lower maximum temperatures, but it will still be very humid."


The possibility of thunderstorms comes from very warm and humid air moving up from the Spanish plains to the UK. If this meets cooler air from the Atlantic, the warm air can be forced rapidly upwards to produce thunderstorms.


Excessive exposure to high temperatures can be dangerous. During the summer heatwave in northern France in August 2003, three weeks of unprecedented high temperatures caused 15,000 deaths, especially among older people. In England that year, over 2,000 more people died during the 10-day August heatwave than during the same period of any of the previous five years.


Since 2003, the UK has seen a significant heatwave in 2006, when there were an estimated 680 more deaths compared with similar periods in previous years, and in 2009, when there were approximately 300 excess summer deaths.


This year the world experienced the hottest May globally since records began in 1880. The record heat, combined with increasingly certain predictions of an El Niño, means experts are now speculating whether 2014 could become the hottest year on record.


Data published by the US National Oceanic and Atmospheric Administration last month showed the average land and ocean surface temperature for May was 0.74C above the 20th-century average of 14.8C (58.6F), making it the highest on record.