When the mercury rises, the UK Health Security Agency (UKHSA) issues colour-coded warnings to help the public and health services prepare for dangerously hot weather. These alerts are not just about discomfort—they signal real risks, from increased hospital admissions to potential deaths among the most vulnerable.
The UKHSA operates a heat health alert system alongside the Met Office. Alerts are typically issued from June to September, when elevated temperatures could affect public health. There are two main levels: an amber alert means “significant impact” is likely across health and care services, while a yellow alert signals “minor impact” is expected, though water-related incidents such as cold water shock and drowning may also increase. The alerts cover specific regions; for example, in June 2026, an amber alert was in place for London, the southeast, southwest and east of England, as well as the Midlands, from midday on a Thursday until the following Tuesday evening. Yellow alerts covered the East and West Midlands.
“An explainer on UK heat health alerts, their levels, impacts, and how to stay safe.”
The system exists because sustained hot weather can cause serious health outcomes. According to the NHS, the most vulnerable groups include older people, especially women over 75, those living alone or in care homes, people with long-term conditions such as heart or lung disease, diabetes, Parkinson’s and some mental health conditions, patients on multiple medicines, babies and very young children, and those dependent on alcohol or drugs or with Alzheimer’s disease. Dr Agostinho Sousa, head of Extreme Events and Health Protection at UKHSA, stresses that “simple steps such as staying hydrated, avoiding the sun during the hottest part of the day, and keeping your home cool” are key to staying safe. Health and social care services in affected regions are urged to prepare for increased pressure.
For UK readers, the practical implications are immediate. During a heatwave, temperatures can soar into the low 30s Celsius, with high humidity making it feel even hotter and leading to uncomfortable nights (overnight temperatures in the high teens in the southeast). Travel can be disrupted: railways may impose speed restrictions because tracks can bend in extreme heat, causing delays and cancellations. Drivers are warned to remove everyday items from parked cars—medications, aerosols, carbonated drinks, phones and battery-powered gadgets—since stationary vehicles can become dangerously hot rapidly. Infants, children, older people and animals should never be left alone in vehicles.
This explainer answers common questions about heat health alerts:
Q: What is a heat health alert? A heat health alert is a warning issued by the UK Health Security Agency (UKHSA) that indicates when high temperatures are likely to affect public health. Alerts are colour-coded: amber for significant impacts on health and care services, and yellow for minor impacts.
Q: Who is most at risk during a heatwave? The most vulnerable are older people (especially women over 75), those with long-term illnesses like heart or lung conditions, diabetes, Parkinson’s, some mental health conditions, babies and young children, and people dependent on alcohol or drugs or with Alzheimer’s disease. People living alone or in care homes are also at higher risk.
Q: How can I protect myself and others during a heat health alert? Stay hydrated, avoid the sun during the hottest part of the day (typically 11am to 3pm), keep your home cool by closing curtains or blinds, and check on elderly relatives, neighbours and those with underlying health conditions. Never leave anyone in a parked car, and remove medications, aerosols and electronics from vehicles.
What happens next depends on the forecast. The Met Office provides updated temperature predictions, and the UKHSA adjusts alert levels accordingly. In June 2026, temperatures were forecast to reach 33°C in parts of England, with a 40% chance of exceeding the UK June maximum temperature record of 35.6°C. The public should monitor local weather reports and follow NHS and UKHSA guidance as the heatwave develops.