More hot weather records have been broken on Tuesday, after London reached an unprecedented May temperature of 35C.
Severe travel disruption has been caused in London as services struggle to cope with the heat.
It comes just one day after the previous all-time high was set in Kew Gardens on Monday afternoon, smashing the previous May peak which stood at 32.8C reached in 1922 and 1944.
The expected high for large swathes of southern England and Wales on Tuesday could creep up to 36C, senior Met Office meteorologist Becky Mitchell said.
Those forecasts span the Midlands, the south-east and south-west England, East Anglia, and South Wales.
A yellow weather warning has been issued for thunderstorms across much of England on Tuesday, the Met Office said.
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Emergency services warn of dangers of swimming during heatwave
Emergency services have warned about the dangers of swimming in open water during the heatwave.
Police forces in South Yorkshire, West Yorkshire, Warwickshire, Lincolnshire and Devon and Cornwall were all called out to separate fatal incidents, involving four teenagers and one man in his 60s.
On Tuesday afternoon, Lancashire Police said searches were under way after a boy got into difficulty while swimming in a river in the Ribble Valley.
It has led the RNLI to warn of the “very real risk” of swimming in open water during the heatwave.
Avanti West Coast London services hit by points and signalling failures
Avanti West Coast warned of disruption to services after points and signalling failures.
“Due to a points failure at London Euston some lines are blocked,” it posted on X.
“Train services running to and from this station may be cancelled or delayed.”
Earlier, it had messaged: “Due to a fault with the signalling system between Milton Keynes Central and Watford Junction, some lines are blocked.
“Train services running through these stations may be cancelled or delayed.”
'Exceptional' heat to continue throughout the week
Met Office chief forecaster Andy Page said the “exceptional” late-spring heat will continue for much of this week, with more “tropical nights” expected.
“Last night provisionally recorded the warmest May night on record, and we’re likely to see further very warm nights in the south over the coming days,” he said.
“There is a chance a few places will experience a ‘tropical night’ in the south of England and in Wales tonight, which is where temperatures don’t fall below 20C.”
The highest temperatures will shift westwards on Wednesday, with northern areas feeling more of the warmth on Thursday, Mr Page said.
Temperatures will return to near-normal by Sunday and there will be an increased chance of showers, he added.
Euston train services hit by high track temperatures
“As a result, trains running between these stations have to run at reduced speed and may be delayed cancelled or revised,” it added.
“This is expected to continue until the end of the day.”
Services that were due to run between East Croydon and Watford Junction were expected to be cancelled or may be diverted to London Victoria.
Delays between Peterborough and London Kings Cross until the end of the day
There have been a number of heat-related incidents between Peterborough and Stevenage today, disrupting some lines running between Peterborough and London Kings Cross.
Trains between these stations will be delayed throughout the rest of the day.
Routes affected include:
- Grand Central between Sunderland / Bradford Interchange and London Kings Cross
- Hull Trains between Beverley / Hull and London Kings Cross
- All LNER routes to / from London Kings Cross
- Lumo between Edinburgh and London Kings Cross
Heat affecting South Western services
Due to multiple signalling faults and heat‑related speed restrictions across the South Western Railway network, trains are required to run at a reduced speed on a number of lines.
This is affecting all South Western Railway routes to and from London Waterloo.
No maximum temperatures for workplaces, says Downing Street
Downing Street has said that they will not mandate setting a maximum legal temperature for workplaces.
A Downing Street spokesperson said that "the government would always encourage people to follow health advice from the UK Health Security Agency in order to keep cool in these temperatures".
The spokesperson added that encouraging people to consider working from home was a “matter for individual employers".
Some countries do have maximum temperatures for workplaces - in Spain the maximum legal working temperature indoors is 27C for sedentary work and 25C for light physical work.
Young people deliberately starting fires in London, say fire chiefs
Young people have been deliberately igniting fires in London which is gripped by a heatwave, say fire chiefs.
The London Fire Brigade (LFB) said it had experienced its busiest period of the year so far over the Bank Holiday weekend.
Crews attended 2,093 incidents over the three days, up 41% compared to 2025, including 20 fires requiring the attendance of four or more fire engines.
Between 7am on Friday 22 May and 7am on Tuesday 26 May, LFB control officers took 3,644 calls, nearly double the number the brigade routinely takes.
Incidents included 10 fire engines called to a converted house alight in Thornton Heath in the early hours of Saturday morning, 50 calls to a fire at a building in Lower Clapton which saw eight fire engines deployed on Saturday evening, eight fire engines sent to a blaze near a railway line in Hackney on Sunday and eight fire engines despatched to a house fire in Tolworth on Monday.
Crews also responded to at least 70 outdoor fires across the capital during this period, including grass, trees and fencing alight as well as fires linked to barbecues.
LFB Assistant Commissioner Paul McCourt said: “The Bank Holiday weekend was a very busy period for us.
“Whilst many of the fires we attended were accidental, some smaller outdoor fires are believed to have been set deliberately, including by young people.
"With it being the half-term holidays and London facing further hot weather, we urge parents and carers to remind young people to act responsibly."
He added: "The risk of wildfire in London remains heightened due to the hot and dry conditions and the consequences of starting a fire could be devastating."
Tuesday officially hottest May day ever
Tuesday is now officially the hottest day in May on record.
Temperatures have provisionally reached 35C at Heathrow and Kew Gardens in London, the Met Office said.
Trains disrupted amid hot temperatures
Train services across Britain are being disrupted as temperatures soar.
Network Rail has imposed a series of speed restrictions on tracks to keep trains safe.
South Western Railway (SWR) issued a general alert to all passengers, stating that services across its entire network “may be revised” because of the hot weather on Tuesday.
It cancelled a number of services scheduled to run in the afternoon and early evening.
This is affecting journeys between London Waterloo and Weymouth via Winchester, Southampton and Bournemouth, and between London Waterloo and Aldershot via Woking and Guildford.
Some services between Exeter St Davids, Salisbury and London Waterloo are only running as far as Basingstoke.