A rare red weather warning has been issued by health chiefs and forecasters as temperatures could hit a record-breaking 40C this week.
Britons have been warned of possible danger to life, with the UK Health Security Agency (UKHSA) and the Met Office issuing red heat health alerts for the East Midlands, West Midlands, East of England, London, South East and South West.
The hot spell could lead to delays on the roads and railways, and emergency services are bracing to help those vulnerable to extreme heat.
The Met Office has said that there is “growing confidence” that this week may break the record for the hottest June temperature of 35.6C, which was last set in 1976 in Southampton.
The weather forecaster said that in this week’s heatwave, parts of England and Wales are likely to see temperatures exceed 37C in the shade and could even see them rise to 40C in some places.
The extreme heat, which has been very rare in the UK until now, will be accompanied by high humidity, and very warm and humid nights, which will make it hard for people to recover overnight, the Met Office said.
Extreme heat on Tuesday, Wednesday, and Thursday
Very high temperatures and high humidity are expected on Tuesday and especially on Wednesday, reaching 35C in some areas on Tuesday and then into the high 30s on Wednesday.
An amber heat alert is in place on Tuesday for the East Midlands, East of England, London and the South East, the South West, Wales and the West Midlands.
The UKHSA has warned that this will lead to a rise in deaths, particularly among those aged 65 and over or with health conditions. There will be increased demand on all health and social care services, and heat will affect people’s ability to go to work.
A rare red warning comes into force at 9am on Wednesday and stays in place until 9pm on Thursday. The “extreme heat” warning covers parts of the East and West Midlands, London and the East of England, South West England, and Wales, with forecasters warning of a “danger to life”.
A wider amber warning is also in place covering parts of the North of England and Yorkshire, where temperatures are expected to reach the low 30s.
Remaining hot on Friday
Temperatures are expected to remain extremely warm on Friday, although there are currently no weather warnings in place.
The mercury could reach as high as 38C in parts of the South East of England, with dry and sunny conditions expected.
It comes as Europe has seen sweltering temperatures across the continent where temperatures up to 44C had been forecast.
Adverse health effects are “likely” in the wider population, including sunburn or heat exhaustion (dehydration, nausea, fatigue) and other heat-related illnesses, the Met Office warned, adding that “changes in working practices [are] required”.
Met Office deputy chief forecaster Tom Crabtree said: “The forecast heatwave is developing into an impactful severe weather event, with record-breaking June temperatures and very high humidity. The combination of heat and humidity will be oppressive and bring impacts across society from public health and infrastructure, to power and water supplies.
“As well as very high daytime temperatures, there will be consecutive nights where temperatures do not drop below 20°C, which is called a Tropical Night. This will make it very hard for people to recover from the daytime heat, exacerbating the heat stress impacts.”
“Very intense humidity” is expected, with the Met Office also warning of a possible increase in water safety incidents due to more people being likely to visit coastal areas, lakes and rivers.
Samantha Hughes is the National Water Safety Partner at the RNLI. She said: “With warmer weather approaching, it’s important to remember that the water is still cold. Entering it unexpectedly can lead to cold water shock, causing a sudden increase in breathing and heart rate, which may trigger panic.
“If you find yourself struggling in the water, remember to Float to Live: tilt your head back so your ears are submerged, relax and control your breathing. You may need to gently use your hands to help you stay afloat, and it’s ok if your legs sink – everyone floats differently.
“Where possible, always choose a lifeguarded beach, and swim between the red and yellow flags. In a coastal emergency, remember to call 999 for the coastguard.”
There is also an increased chance that some heat-sensitive systems and equipment may fail, leading to power cuts and the loss of other services to some homes and businesses, it added.
Delays to road, rail and air travel are also possible, with potential for welfare issues for those who experience prolonged delays.
People in the alert area are advised to drink plenty of fluids and to keep out of the sun, and avoid exercising between 11am and 3pm, the Met Office said.
