UK records highest ever May temperature for second day in a row

The UK has recorded its highest-ever May temperature for the second consecutive day, as thermometers hit 35C (95F) at Heathrow and Kew Gardens in London, the Met Office said.

The latest high was recorded the day after the country’s provisional hottest meteorological spring temperature of 34.8C in Kew Gardens in south-west London. The previous May peak of 32.8C had stood since 1922.

The Met Office issued a yellow weather warning for thunderstorms across England earlier on Tuesday. Forecasters said isolated storms with lightning, hail and gusty winds could affect large parts of the country, from Bath and Reading to Lincoln and Sheffield.

The Met Office said many areas would stay hot and sunny, but that there was potential for as much as 30mm of rainfall in the space of an hour in some parts. The warning will be in effect from 3pm to 10pm.

Police reported two deaths over the bank holiday weekend. A 13-year-old boy died on Monday after getting into difficulty in a West Yorkshire reservoir. Police said he was pulled from the water and taken to hospital, where he was pronounced dead.

South Yorkshire police said the body of a second boy had been found in the early hours of Tuesday after he was last seen entering the water at a park in Rotherham the day before.

The country experienced a “tropical night” on Monday, defined as when temperatures do not fall below 20C. Kenley Airfield in south London recorded an overnight temperature of 21.3C.

Many places across England and Wales will reach the heatwave threshold on Tuesday, and some will have experienced such conditions for five days by Wednesday, the Met office’s senior meteorologist, Becky Mitchell, said.

Bournemouth beach on bank holiday Monday. Photograph: Finnbarr Webster/Getty Images

To qualify as a heatwave, temperatures must meet or surpass a specific threshold for three consecutive days. The highest heatwave threshold in the UK at this time of year is 28C, which applies to London and areas north of the capital towards Cambridgeshire.

Heatwave conditions were already met in eight parts of England by Sunday night: Heathrow, Kew Gardens and Northolt in London; Benson in Oxfordshire; Brooms Barn and Santon Downham in Suffolk; and High Beech and Writtle in Essex. Mitchell said that number would increase after the bank holiday weather, but the data was yet to be released.

Temperatures are forecast to start to decline from the middle of the week, but it is still expected to be largely dry with sunny spells. Many areas are still likely to experience temperatures in the high 20s.

Temperatures in eastern areas, however, are forecast to be lower by about 10C as a brisk easterly wind develops.

If validated, the latest May record means highest ever temperatures have been set for seven months of the year since 2003.

A previous Met Office study found breaking the May record was “around three times more likely now in our current climate than it would have been in a natural climate not impacted by greenhouse gas emissions”. This means that something once judged a one-in-a-100-year event was now a one-in-33-year event, it said.

In contrast, there were lows of -5C in Scotland last week when daytime temperatures more widely peaked at about 14C to 15C.

Amid the bank holiday heat, firefighters worked through the night to tackle a grass fire near Arthur’s Seat in Edinburgh as temperatures in the city hit 25C.

Clouds of smoke were seen rising from the area around the natural landmark and local residents were advised to keep their windows and doors shut as a precaution.