Rare red warnings have been issued over extreme temperatures that are set to hit record highs for June this week, with impacts on health, schools, workers and transport.
Forecasters say the heatwave could see temperatures hit 38C to 40C in some parts of England and Wales, smashing the June record set in 1976 by several degrees as human-driven climate change intensifies the impact of a “heat-dome” settling over western Europe.
The hot conditions, which have been very rare in the UK until now, will be accompanied by high humidity and very warm nights, which will make it hard for people to recover overnight, the forecasters added.
The Met Office issued a rare red weather warning covering an area stretching from London to Swansea and Somerset to Birmingham from 9am on Wednesday to 9pm on Thursday.
These are reserved for the most severe events, the agency said, meaning this heatwave is expected to bring “severe and significant impacts” including widespread health risks for many, not just those who are normally more vulnerable to the heat, and even danger to life.
The alert also warns that “substantial changes” in working practices and daily routines will be required, and indicates a high risk of failure of heat-sensitive systems and equipment, bringing the loss of power and other essential services, such as water, electricity, gas or mobile phone services.
An amber weather warning is also in place for a larger area of England and Wales between Monday and Thursday.
Dr Will Lang, chief meteorologist at the Met Office, said: “We are forecasting extreme temperatures in the next few days, particularly on Wednesday and Thursday, when it looks like we’ll be seeing maximum temperatures into the high 30s.
“But also we are stressing very high overnight temperatures which will be very uncomfortable for vulnerable groups, and very humid conditions as well.”
Dr Lang told the Press Association the conditions would far exceed the heat seen in June in the past, and was on “a much bigger scale” than the heatwave the UK experienced recently at the end of May.
The extreme heat would be of greater longevity than the record heatwave in 2022, when, for a “short, sharp” period, temperatures climbed above 40C in some places for the first time ever in the UK, he said.
The UK Health Security Agency (UKHSA) also issued a red health warning for six regions of England – the West Midlands, East Midlands, South East, South West, London, and east of England – from 1am on Wednesday until 11pm on Thursday.
This indicates “a risk to life for even the healthy population” as well as impacts beyond health and social care, with potential effects on transport systems, food, water, energy supplies and businesses.
It is the second red heat health warning to be issued, after the first in July 2022 when temperatures soared above 40C in the UK for the first time.
A separate amber health alert has also been put in place for the North West, North East, and Yorkshire and the Humber for the same period, the agency said, meaning the impact is expected to be felt across the whole of the health service in these areas.
Dr Agostinho Sousa, head of extreme events and health protection at the UKHSA, said: “It is vitally important that people understand the risk posed by high temperatures like these, and take steps to keep themselves and their friends, families and neighbours safe.”
As people flock outdoors to enjoy the sunshine and cool down, fire chiefs urged the public to take extra care in outdoor spaces with the increased risk of wildfires and water-related deaths.
Phil Garrigan, National Fire Chiefs Council (NFCC) chairman, said: “We have already seen the consequences that periods of extreme heat can have, with a number of lives tragically lost in water-related incidents during recent hot weather.”
People can also expect travel disruptions, including delays on roads and road closures as well as delays and cancellations to rail and air travel, the Met Office said.
Rod Dennis, road safety spokesperson at the RAC, warned that there could be a record number of breakdowns this week as the heat puts extra strain on vehicles and urged drivers to avoid non-essential journeys if their vehicles do not have effective air conditioning.
“The heatwave will affect services right across the UK and while all patrols will be working incredibly hard to assist drivers, longer waits are more likely,” he said, adding that some simple basic checks under the bonnet could reduce the risk of breakdowns.
The AA said drivers could also see gritters out on some roads this week with the potential for surfaces to soften or become sticky under the heat, with heavy traffic even causing them to rut in some places.
Edmund King, AA president, said: “If drivers come across a softened or damaged surface, they should slow down, avoid harsh braking or steering, and leave extra space from the vehicle in front.”
Meanwhile, the National Association of Head Teachers (NAHT) said it has written to all its members with guidance on dealing with the heat this week, including the impact on pupils and staff, legal positions and when to consider closure.
Paul Whiteman, NAHT general secretary, said: “While there is no legal ‘upper limit’ for temperature in schools, (school leaders) will certainly be doing all they can to mitigate the effects of such high temperatures.”
And employers are being urged to assess any risks to workers as the heatwave kicks in, with conciliation service Acas saying they should assess any risks and discuss what they need to do, such as providing fans, portable air-cooling units, allowing more frequent or longer breaks and relaxing rules for wearing ties or suits.
Ruth Wilkinson, of the Institution of Occupational Safety and Health, also warned that outdoor workers – such as those in agriculture, construction and the gig economy – “face the most immediate risks” but poor ventilation and lack of cooling infrastructure also leaves many indoor workers facing stifling conditions.
Scientists said the cause of the heatwave is a so-called “heat dome”, which involves a high-pressure weather system acting like a lid trapping in the heat over a region.
Akshay Deoras, senior research scientist at the National Centre for Atmospheric Science at the University of Reading, said: “This is not just a heatwave, it is a heat-dome driven furnace that will grip most of southern UK and push temperatures into truly exceptional territory.”
He added that human-driven climate change “has provided the springboard for this event” after loading the atmosphere with extra heat and making extreme temperatures far more intense than they would have been in the past.
Bill McGuire, professor emeritus of geophysical and climate hazards at University College London, said temperatures of more than 43C are now possible in the UK’s current climate, with heatwaves lasting for multiple days.
But the country’s health services, energy infrastructure and transport are “simply not built for these conditions”, he warned.
And Gareth Redmond-King, head of international at the Energy and Climate Intelligence Unit, said the heatwave “hits in the week Parliament is set to debate and vote on the UK’s plans to get to net zero – which remains the only scientifically available solution to halting climate change, and limiting these dangerous and costly extremes into the future”.
He added: “Let’s be clear, temperatures will continue to go up and up until we reach net-zero emissions.”
Last week, the national drought group, which brings together the Met Office, regulators, government, water companies, farmers, scientists and conservation organisations, said the risk of drought has risen as East Anglia returns to the status of “prolonged dry weather” and while Devon and Cornwall are on a watchlist.
Farmers are also facing growing pressure, the group said, with many reporting issues with the growth of spring crops which forced them to start taking water from rivers and lakes to sustain crops in dry soil earlier than usual this year.
Officials said the Environment Agency is working with water companies on their drought plans and is actively monitoring water levels and rainfall patterns.
