The UK record for the hottest day in June was broken for a third day in a row on Friday, with temperatures reaching 37.3C in Suffolk, the Met Office has said.

The 50-year-old record was beaten by more than a full degree, highlighting the intensity of the heatwave which has gripped the country this week.

It has resulted in travel disruption, hundreds of schools closing, and six NHS trusts declaring critical incidents after being overwhelmed with patients.

But the scorching heat is expected to ease off over the weekend, and a yellow warning for thunderstorms has been issued for Scotland and parts of northern England.

The provisional hottest June temperature was recorded in Santon Downham on Friday.

It surpassed the high of 36.7C in Merryfield, Somerset, on Thursday, which followed 36.1C (97F) recorded in Gosport, Hampshire the previous day.

Wales saw a peak of 35.1C in the village in Flintshire, and Scotland's highest temperature of 29.2C was recorded in Dumfries and Galloway.

It was cooler in Northern Ireland, where a high of 25.6C was recorded in County Down.

All four nations have experienced their highest temperatures of the year so far this week, with sweltering conditions of more than 20C continuing through the night for many in England and Wales - in what forecasters refer to as "tropical nights".

Red warnings for extreme heat - meaning there is a population-wide risk of adverse health affects or danger to life - in place across London, the east and the south east end at 21:00 BST on Friday.

There are also amber heat warnings in place until Saturday evening for south-west England.

Health services have come under strain in some parts of the country.

As well as the NHS dealing with an increase in emergency patients suffering heat-related illnesses, Dr Hilary Williams, clinical vice-president at the Royal College of Physicians, said MRI machines and scanners had been affected by the heat.

She told BBC Radio 4's Today programme "basic ward infrastructure" had been unable to cope, adding: "The patients are far too hot, we're hearing reports of elderly care wards way over 30C."

Meanwhile the London Ambulance Service (LAS) had seen about a 50% increase in 999 calls during the heatwave, its head Jason Killens told the BBC, a trend he thought would be seen across the country.

Killens said LAS had cancelled all non-essential training and meetings to deploy more staff to the front line.

At least 600 schools in England either completely or partially closed due to the heat on Friday, after a week in which more than 2,000 schools in England and Wales that shut their doors. Exact numbers on school closures were not available.

In Leicestershire, the family of a teenage boy who became the latest to drown while swimming in open water during the hot weather paid tribute to him.

In a statement, they said 13-year-old Hayden Jones-Powell would be remembered for his "big smile", as authorities reissued warnings about the hidden risks of getting into open water.

Travel disruption continued into Friday evening rush hour for some, with some delays and cancellations.

Avanti West Coast, Great Western Railway and Transport for London announced changes to services because of the heat.

There were closures at some of the UK's most well-known tourist attractions.

London's Tower Bridge, Cutty Sark and Royal Observatory closed to visitors, as did Marwell Zoo in Hampshire.

Thorpe Park, Chessington World of Adventures and Legoland Windsor allowed people to swap tickets for a different day.

Firefighters contained a wildfire in Derbyshire that had affected around 200 hectares (990 acres) of land on Tintwistle Moor since Wednesday.

The heatwave - which has affected other parts of Europe - is being driven by a "heat dome", an area of high pressure that traps heat, settling over western Europe.

The high humidity accompanying the heat has exacerbated the potential for health impacts, the Met Office said.

Some areas have seen intense thunderstorms triggered by the heat, including in Edinburgh, where the airport said there had been significant disruption.

While it is hard to link climate change to individual extreme weather events, scientists say climate change is making heatwaves more frequent and intense.

Friday night will be less warm but temperatures in south-east England and East Anglia may still not drop below 20C.

This weekend is expected to continue to be hot for many, but only south-east and eastern England will continue to be covered by an amber heat weather warning on Saturday.

In Scotland, a yellow warning for thunderstorms will remain in place until the early hours of the morning.

Temperatures could pass 30C in some areas again on Sunday, though no Met Office weather warnings are in place.