What is a Met Office 'red' health alert for heat?
How hot will it be this week in the UK? What does a Met Office 'red' alert mean for heat? What precautions can be taken to stay safe in the sun?
The Met Office has upgraded its amber heat warnings for Wednesday and Thursday, replacing them with rare red warnings for extreme heat.
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June’s all-time daily record temperature is forecast to be broken this week when the heat strikes central and southern England at times.
The overpowering sunshine follows on from 41C heat in France, and in the UK, the heat is expected to bring disruption to public services and transport.
It will be the highest UK temperatures since 2022, but the high humidity is expected to make the conditions feel more severe this time around.
Read also: Rare red 'danger to life' weather warning for extreme heat issued as temperatures set to hit 40C
How hot will it be this week in the UK?
The peak of the heatwave is forecast for Wednesday and Thursday, when temperatures are expected to climb to at least 39C, and possibly beyond that in some regions.
The current highest temperature on record for June is 35.6C but this could be smashed with two days of 40C forecast for the southern parts of the country.
An exceptional heatwave is developing this week with record-breaking June temperatures highly likely, particularly for England and Wales 🌡️
— Met Office (@metoffice) June 22, 2026
Following the heat in May 2026, it would be the first time since 1911 that two consecutive months have observed record temperatures pic.twitter.com/YuDc8gMcWO
What does a Met Office 'red' alert mean for heat?
The Met Office has stated that a "red" alert for hot weather means:
- Population-wide risk of adverse health effects, not just the most vulnerable,
- Substantial changes in working practices and routines required,
- High risk of failure of technology and services that are affected by the heat, including water, electricity, gas or mobile phone services,
- Significant increase in people visiting coastal areas, lakes and rivers, leading to an increased risk of water safety incidents,
- Delays on roads and road closures, along with delays and cancellations to rail and air travel.
Met Office deputy chief forecaster, Mark Sidaway, said: “Red warnings are reserved for the most severe events and we’re expecting severe and significant impacts from this heatwave, with health impacts likely for many, even beyond those who are normally more vulnerable to the heat.
“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.”
What precautions can be taken to stay safe in the sun?
As well as wearing sun cream and protection if heading out, direct exposure and physical tasks should be avoided during the peak of the warmth.
The RNLI has also communicated the dangers of cold water, which is not as warm in June as it will be later in the summer.
Samantha Hughes, at the RNLI, 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.”