LONDON, United Kingdom (AFP) — The United Kingdom (UK) broke the record for a June temperature for the third day in a row on Friday, the Met Office weather agency said, as a sweltering heatwave strained schools and hospitals and drove down business.

A provisional 37.3C record temperature was chalked up in Santon Downham, a village in Suffolk, in southeast England, the Met Office told AFP, breaking the previous high of 36.9C set earlier Friday.

Before this week, the UK’s 1976 record temperature for June of 35.6C “had stood for 50 years, but — provisionally — it has been exceeded on three consecutive days this week”, said Met Office climate spokesman Grahame Madge.

“Today marks the peak of the heatwave in terms of temperatures,” Chief Forecaster Andy Page said in a statement.

The Met Office has issued its highest level red “extreme heat” warning for an unprecedented three days in a row until Friday evening.

It has warned of “population-wide adverse health effects” as doctors, teachers and climate experts cautioned that the UK was unprepared for increasingly frequent heatwaves due to climate change.

The electricity grid operator NESO issued a new warning that supply margins could be tighter during the peak demand period on Friday evening due to pressure on the system.

At a market in central London, which mainly caters to office workers, street food vendors were struggling to work beside the gas-fired stoves, and footfall was down.

“I do just want to stick my face in the ice bucket,” said 37-year-old turkey stall owner Will Evans, sporting a green cooling towel he bought online as a bandana.

Working under a black canopy, the chef said it got up to 5C hotter in his workspace, compared to the temperature outside the tent.

According to Evans, public advice to remain at home and limit travel meant fewer office workers were buying lunch at the market.

At a nearby fried chicken stall, Rainei Almeida said it felt as hot as 43C due to the fryers.

“It’s going to be a difficult summer for everyone here in the market, the traders, unfortunately,” said the 27-year-old stall worker from Ecuador.

Hospitals and emergency services were stretched thin as well, with London Ambulance Service recording the highest number of “life-threatening” emergency calls in a day on Wednesday, driven by the heat.

“Clinical colleagues who aren’t routinely deployed on the front line have been deployed back on the front line,” London Ambulance Service Chief Jason Killens told BBC Radio 4.

Meanwhile some tourist attractions and museums in London were closed on Friday due to the red heat warning, including the iconic Tower Bridge and the Royal Observatory in Greenwich.

The British Museum said it was closing early and warned it “may also temporarily close some galleries”.

Hundreds of schools remained closed or partially closed on Friday, and multiple hospital trusts had raised the alarm after MRI machines and IT systems broke down in the heat.

A wildfire which broke out on Wednesday on moorland near the northwestern town of Glossop was contained by Friday afternoon, fire services said.