The Met Office has issued an amber extreme heat warning across large parts of England and Wales, with temperatures forecast to reach 37°C in some areas and a chance that the June record of 35.6°C could be broken. For many, this is the first time they have encountered such a warning, but heatwaves are becoming more frequent and intense due to human-induced climate change.
A heatwave in the UK is defined by local temperature thresholds. For a hot spell to officially become a heatwave, temperatures must exceed a threshold – which varies from 25°C to 28°C in different parts of the country – for three consecutive days. In London and the South East, that threshold is 28°C or 27°C. The Met Office amber extreme heat warning is a relatively new alert, introduced in 2021. This is only the sixth such warning issued since then. It means that there are likely to be widespread impacts on people and infrastructure, including adverse health effects, disruption to travel, and increased risk of water safety incidents.
“What a UK heatwave is, how extreme heat warnings work, and what the current amber alert means”
The current heatwave is building over the weekend, with temperatures already reaching the low 30s in the south and east. By Monday and Tuesday, temperatures are expected to peak at 35–37°C in south-east England, with high humidity making it feel even warmer. 'Tropical nights' – where the overnight temperature does not drop below 20°C – are also likely, especially in urban areas. This combination of high daytime heat and warm nights can be dangerous, as the body gets less chance to cool down.
The UK Health Security Agency (UKHSA) has also issued amber heat health alerts for the East, South East, South West, and London, and yellow alerts for the East and West Midlands. These alerts are separate from the Met Office warnings but highlight the increased risk to life for vulnerable people, such as the elderly, those with underlying health conditions, and young children. The UKHSA is urging health and social care services to be prepared and reminding people to look out for relatives and neighbours.
For UK readers, the practical impacts are significant. High UV and pollen levels are anticipated in many areas, affecting those with allergies or skin sensitivities. The RNLI has warned about water safety, as more people head to the coast and inland waters to cool off. Travel disruption is also possible, as rail tracks and roads may be affected by the heat. The amber warning covers London, the east and south-east of England, parts of the south-west of England, and Wales – meaning millions of people are directly affected.
Q: What is the difference between a heatwave and an extreme heat warning? A heatwave is a meteorological term: three consecutive days above a local temperature threshold (e.g., 28°C in London). An extreme heat warning is a Met Office alert that indicates likely widespread impacts on health and infrastructure. Amber is the second-highest level, meaning impacts are expected, and the public should take action.
Q: How do 'tropical nights' affect health? When overnight temperatures stay above 20°C, the body has less time to recover from daytime heat. This increases the risk of heat-related illness, especially for older people, those with chronic conditions, and people who cannot cool their homes effectively.
Q: Which areas are affected by the current heatwave? The amber extreme heat warning applies to London, east and south-east England, parts of south-west England, and Wales. The highest temperatures, up to 37°C, are forecast for south-east England. Other parts of the UK, including Scotland and Northern Ireland, will see cooler conditions in the high teens to low 20s.
What happens next: Temperatures are set to peak on Monday and Tuesday, then drop slightly by Thursday, though the south-east may still reach 34°C. The June record of 35.6°C, set in Southampton in 1976, could be broken. The Met Office will continue to monitor the situation and may issue further warnings as confidence increases on the length and reach of the hot spell.