The UK is experiencing the hottest day of the year so far, with temperatures forecast to continue to climb above 30C over the bank holiday weekend.
Temperatures reached 28.4C at Heathrow in west London, Cranwell in Lincolnshire and Cambridge on Friday afternoon, the Met Office confirmed. The current May record is 32.8C.
Amber health alerts have been issued for parts of England as families attempt a half-term getaway.
Transport networks are expected to be busy over the bank holiday weekend. Passengers travelling to Europe from the Port of Dover earlier faced delays of several hours, due to the introduction of a new entry and exit system.
There have been warnings of potential congestion on roads to the port between Friday and Sunday, with some 18,000 cars expected to pass through.
The UK will see hotter temperatures than parts of Africa and the Mediterranean over the next five days, with hot, humid air pushing its way across north-west Europe.
The warmest day of the year in the UK was recorded on Friday, with temperatures reaching 28.4C in some areas - breaking the previous high of 26.6C at London's Kew Gardens on 8 April.
Coningsby in Lincolnshire and Kew Gardens in London also saw temperatures reach 28.3C, while Wellesbourne in Warwickshire saw a high of 28.2C.
Cardiff reached 25.8C, making it Wales's warmest day of the year so far too.
The UK Health Security Agency has issued amber heat health alerts for the Midlands, eastern and south-east England - these alerts were upgraded from yellow on Friday morning.
An amber alert means there is a risk of a significant impact across health and social care services, with children and those aged over 65 at risk of negative health implications.
The rest of England is under yellow heat health alerts, meaning adverse weather is "likely to affect vulnerable groups".
By Wednesday, some areas are expected to be under heatwave conditions - which is defined by the Met Office as at least three consecutive days where daily maximum temperatures exceed a county-specific threshold.
Cloudier skies over Scotland and Northern Ireland mean temperatures there will be lower - reaching between 17C and 22C this weekend.
Wembley Stadium has advised football fans heading to the English Football League's play-off finals to take extra care - dressing accordingly and staying hydrated throughout the day.
Around 170,000 fans are expected across three days of fixtures in the capital, while games are planned across England on Sunday for the last day of the Premier League season.
Transport networks across the country are expecting large numbers of travellers over the bank holiday weekend.
More than 19 million people are expected to be on the roads, the RAC estimates - a million more than during the late May bank holiday last year.
UK motorways are expected to be the most congested on Friday and Saturday as people make the most of the bank holiday weekend.
National Highways urged drivers to carry out vehicle checks, take plenty of drinking water and pack summer supplies including sunglasses and a hat on long journeys during the heatwave.
And the sunny weather is playing a role in the traffic, Sean Kimberlin, RAC mobile servicing and repairs team leader, said.
He added that it was set to be the "busiest late May bank holiday since 2024" despite concerns over high fuel prices.
Train lines are also expected to have a higher number of passengers this weekend, with Southern Railway warning routes to coastal destinations will be particularly busy.
Several operators have scheduled engineering work to take place over the weekend, including on the East Coast Main Line, Transpennine, Great Western Main Line and Thameslink.
Network Rail, which manages many of the UK's railways, has advised those travelling in areas seeing warm weather to allow more time for journeys and carry water bottles.
Meanwhile, passengers have reported long queues at security at Birmingham Airport.
Some travellers told the BBC they narrowly made their flights. A spokesperson for the airport said the delays had been caused by "an unexpectedly high level of staff absence".
The Port of Dover said wait times there rose to two hours on Friday afternoon, but had later fallen to an hour.
It explained the delay was due to the introduction of the new EU Entry Exit System (EES) registration process - which digitally records biometric information - being implemented by French authorities.
The port said it was "working hard" to improve the situation and urged customers to keep to main roads to help with traffic processing and to keep the town of Dover clear for local residents.
At Dover, where people go through the French border before they board a cross-Channel ferry, French authorities have not yet switched on the machines that will take fingerprints and photos under EES.
However, border officials still have to create profiles for travellers linked to the new system, meaning it is taking longer to get through border checks.
Border authorities are allowed to suspend EES altogether if severe delays build up.
