A four-day amber warning for extreme heat has been issued by the Met Office, with parts of England expected to hit 38C — a temperature that could break the June record of 35.6C set in Southampton in 1976. For many UK readers, this is not just a weather story; it's a system designed to protect lives, and understanding how it works is increasingly vital.
So what exactly is an extreme heat warning? The Met Office introduced these warnings in 2021 to alert the public when temperatures are forecast to be so high that they pose a serious risk to health and infrastructure. The one currently in force is an amber warning, which means population-wide impacts are likely. It runs from 01:00 BST on Monday to 23:59 BST on Thursday, covering large parts of England and Wales. The warning is the sixth amber extreme heat warning since the system began.
“A UK explainer on extreme heat warnings, their meaning, health risks, and practical advice.”
The background to these warnings lies in the UK's heatwave definition. For a hot spell to officially become a heatwave, temperatures must exceed a threshold — which varies from 25C to 28C depending on the region — for three consecutive days. The current event is expected to meet that threshold, and the heat is spreading from continental Europe, where an intense hot spell has developed. Overnight temperatures will also remain high, with urban areas struggling to fall below 20-21C, creating so-called "tropical nights" that increase health risks.
Why does this matter for UK readers? The amber warning means serious health risks are possible not just for vulnerable groups but for the wider population. The UK Health Security Agency has issued amber heat health alerts for the South East, East of England, London, the Midlands and the South West, warning of increased demand on health and care services. Yellow alerts are in place for the North East, North West and Yorkshire and The Humber. Dr Agostinho Sousa, head of extreme events and health protection at UKHSA, urged people to look out for elderly relatives, neighbours, and those with underlying health conditions. There are also practical impacts: transport and energy networks may face pressure, and water safety is a particular concern, with the RNLI warning of cold water shock even on hot days. High UV and pollen levels are also expected.
Q: What do the different heat warning levels mean? The Met Office uses three levels: yellow (be aware), amber (be prepared — population-wide impacts likely), and red (emergency — risk of serious illness or danger to life). The current warning is amber, meaning adverse health effects are likely across the population.
Q: Can I leave work if it's too hot? There is no law for a maximum workplace temperature in the UK. The government advises that temperatures must be "reasonable", but no specific maximum is set. The Trades Union Congress has campaigned for a legal limit of 30C (27C for strenuous work), but this has not been enforced. If your workplace is uncomfortably hot, you should speak to your employer.
Q: How do I stay safe during an extreme heat warning? The Met Office and UKHSA advise staying out of the sun during peak hours (11am-3pm), keeping hydrated, closing curtains in rooms that face the sun, and checking on vulnerable people. Never leave anyone in a closed, parked vehicle. If swimming, be aware of cold water shock and only swim at lifeguarded beaches.
What happens next depends on the weather patterns. The amber warning currently runs until Thursday, but it may be updated as confidence in the forecast changes. Temperatures are expected to peak on Tuesday and Wednesday, with a chance of breaking the June record. Beyond this week, the hot spell is linked to a heat dome over Europe, and while the UK event may end, the underlying trend of more frequent heatwaves due to climate change is likely to continue.