Britain is waking from the hottest May night on record as millions of people head back to work this morning after a sweltering Bank Holiday weekend. 

Temperatures did not drop below 21.3C overnight at Kenley Airfield, south London, making it a ‘tropical night’, the Met Office said.

The mercury is set to rise even further today to a record-breaking 36C – after the UK experienced its hottest Bank Holiday of all time yesterday. 

A searing 34.8C was recorded in Kew Gardens, south-west London – which also surpassed the highest May day temperature of 32.8C recorded in 1944. 

It comes as millions prepare to head back to air-conditioned offices this morning on packed trains, tubes and buses. 

Transport for London has advised people using its services to carry water with them when travelling. 

Yesterday, tens of thousands of Britons flocked to the coast and beauty spots to bask in the blistering heat despite official government guidance to stay out of the sun. 

A 13-year-old boy died after getting into difficulty while swimming at Leadbeater Dam in Halifax. 

His body was pulled from the water at 3.18pm yesterday and he was taken to hospital where he was pronounced dead. 

People travel in a busy Jubilee Line train carriage on the London Underground during the hot weather in central London yesterday 

The days sun rises over the countryside in Oxfordshire on what is set to be another hot day of weather

A woman cools off in front of a large fan at a London Underground station

Brits were seen lounging on Bournemouth beach in Dorset early on Bank Holiday Monday 

The Met Office said the 34.8C heat is ‘exceptional in the UK even in mid-summer, let alone in May’.

Wales saw its hottest ever temperature in May on Monday evening, with 32.2C recorded at Hawarden Airport in Flintshire. 

The previous record of 30.6C in Newport stood for 82 years.

Greater London, Surrey, Norfolk and Oxfordshire also saw temperatures soar above 32C. 

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 north of the capital towards Cambridgeshire.

Temperatures will start to gradually decline from the middle of the week but it will still be largely dry with sunny spells.

Many will still experience temperatures in the high 20Cs.

However, they will lower by around 10C in eastern areas as a brisk easterly wind develops.

Tourists gather in sweltering temperatures to watch the Changing of The Guard, outside Buckingham Palace yesterday

Youngsters were seen taking a dip in the sea in Southend on Bank Holiday Monday

If validated, the latest May record means seven of the 12 monthly highs have been set since 2003, the Met Office said.

A previous study by the forecasters found breaking that record ‘is 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 the once one-in-a-hundred year event is now a one-in-33 event, it said.

It comes after last week saw lows of minus 5C in Scotland and daytime temperatures more widely peaked at about 14C to 15C.

‘We see these changes happening so much more dramatically,’ Met Office senior forecaster Greg Dewhurst said on Monday morning, adding that climate change is boosting the heat.

‘In the past, heatwaves built and built and built and built over days and days and days – these now just develop so quickly.’

Amber and yellow health alerts remain in place across England, as temperatures continue to soar. 

Tens of thousands of Britons descended on beaches on Monday, including in Bournemouth (pictured)

Tom Kopke, 24, winner of the first men’s downhill race during the annual cheese rolling at Cooper’s Hill in Brockworth, Gloucestershire

Thousands were pictured luxuriating in the heat at seafronts including in Brighton, Bournemouth, Lyme Regis and Devon – while many more swarmed at local lidos and nearby rivers over the three-day weekend.

Others braved the sweltering conditions to watch the annual cheese rolling at Cooper’s Hill in Brockworth, Gloucestershire.

German YouTuber Tom Kopke won the first downhill men’s race. While 11-year-old boy William, the son of 23-time champion and Guinness World Record winner Chris Anderson, won the first children’s uphill race.

Meanwhile, revellers did not let the heat stop them partying at Bank Holiday festivals over the weekend – including the BBC Radio 1’s Big Weekend at Herrington Country Park, Sunderland, as well as star-studded events in Brockwell Park, south London.

However, tragedy struck when a man died on a packed beach in Hastings on Sunday.

Emergency services including an air ambulance scrambled to the scene after a ‘medical incident’.

The man tragically passed away at the scene, on the beach near Warrior Square in St Leonards.

A spokesperson for Sussex Police said: ‘Emergency services responded to a medical incident on the beach near Warrior Square, St Leonards, following concerns for a man’s welfare.

People are seen soaking up the sun while sitting on Jubilee Beach in Southend on Monday

Animal lovers take part in Alpaca yoga at Hope Farm, Dorset

Authorities have warned about the dangers of swimming in reservoirs and lakes over the weekend.

About 500 properties supplied by South East Water have been hit by issues including outages and low pressure as temperatures soar.

The water firm apologised after it had to hand out bottled water to some of its customers in Kent and Sussex.

A total of 250 properties in three Kent villages were suffering intermittent water outages or low pressure on Monday.

A burst water main in Eastbourne, East Sussex, affected 168 properties, while 64 customers suffered from issues with booster pumps at Radfall near Broomfield Gate in Whitstable, Kent.

There were also ‘ongoing water supply problems’ for fewer than 20 properties on higher ground in the Ulcombe area of Kent.

South East Water incident manager Steve Benton said in a statement on Monday: ‘We’re sorry to all impacted customers for the disruption caused.

‘We know water supply issues during hot weather are deeply frustrating and incredibly inconvenient and we are working as quickly and safely as possible to resolve them.’

He added: ‘As a result of the recent hot weather, we’re seeing increased demand across our network and we’re having to pump far more drinking water than usual.

A man tells his dog to go fetch at water fountains in Battersea Park, south west London

‘We’re working hard to maintain supplies to customers across our network as the hot weather and increased demand for drinking water continues.

‘Some customers on higher ground may, however, experience low water pressure or intermittent supply at peak times.’

‘Officers assisted with the emergency response after the incident was reported at 11am on 24 May. Sadly, despite the best efforts of paramedics, the man was declared deceased at the scene.

‘His next of kin have been informed and our thoughts are with them at this difficult time. There were no suspicious circumstances and a report will be prepared for HM Coroner.’

Elsewhere, in Lincoln, the body of 15-year-old Declan Sawyer was recovered at Swanholme Lakes after he disappeared while swimming with a group of friends during the heatwave.

A Lincolnshire Police spokesman said: ‘We can update that our dive team have sadly found a body in the water at Swanholme Lakes, Lincoln. With agreement from the family, we can share that the boy who died is 15-year-old Declan Sawyer.

‘Our thoughts are with his family, and we send our condolences at this incredibly difficult time. This is such a sad incident that will no doubt also affect many of Declan’s friends and the local community as well.’