The UK Health Security Agency (UKHSA) issues Heat-Health Alerts (HHAs) and Heat-Health Planners in collaboration with the Met Office, a arrangement that began on 1 June 2024, according to the agency's hot weather communications toolkit1. The core alerting season for HHAs runs between 1 June and 30 September, although the wider Weather-Health Alerting system is operational year-round1.
Within the core season, a Heat-Health Planner is issued every Monday and Friday, providing horizon scanning for the next 5 days, 6 to 15 days, and 16 to 30 days ahead1. Alerts carry a colour, yellow, amber or red, based on the combination of the impact the weather conditions could have and the likelihood of those impacts being realised, assessed in conjunction with the Met Office1. The toolkit describes the levels as follows1:
| Alert | Meaning given by UKHSA |
|---|---|
| Yellow (response) | Heat unlikely to impact most people but could impact those particularly at risk |
| Amber (enhanced response) | Impacts likely to be felt across the whole health service, with potential for the whole population to be at risk |
| Red (emergency response) | Significant risk to life for even the healthy population |
The HHA targets the health and social care sector and the responder community, while the Met Office's Extreme Heat warnings under the National Severe Weather Warning Service have a wider audience including the public; the HHA issues yellow to red alerts, whereas the national service issues only amber and red for extreme heat1. The two have been aligned since summer 20211. The toolkit notes that the impact-based alert colours are not typically used in public facing communications, and that alert status is publicly available on the UKHSA Data Dashboard1. Individuals and organisations wishing to receive the alerts must register, and can specify which regions they wish to receive alerts for1.
The toolkit sets out the groups at higher risk of becoming seriously unwell in hot weather, including older people aged 65 and over, a change from previous guidance of 75 and above, babies and young children aged 5 and under, and people with underlying health conditions, particularly heart problems, breathing problems, dementia, diabetes, kidney disease, Parkinson's disease or mobility problems1. It also lists pregnant women, people on certain medications, people with serious mental health problems, people who are already ill and dehydrated, people who experience alcohol or drug dependence, people who are physically active or work outside, and people experiencing homelessness1.
"It is estimated that 2,117 people aged 65 years and over died due to the heat in England in 2023"
The same document states that in July 2022 temperatures exceeded 40°C for the first time on record, and that the number of heat-related deaths per year may triple by 20501. The Adverse Weather and Health Plan, which the alerting system underpins, was first published in April 2023 and has been updated for 2025/261.
Why it matters for households
The alerts are issued to the health and social care sector and responder organisations, so households may not see the colour-coded warnings directly; the toolkit states that alert status is publicly available on the UKHSA Data Dashboard, and that those wanting the alerts must register and can choose their regions1. The change to the at-risk age group, from 75 and over to 65 and over, means more households fall within the group UKHSA identifies as at higher risk1. The toolkit states that many of the harms linked to heat exposure are preventable if a few simple actions are taken1. The Heat-Health Alerts: Yellow, Amber and Red Explained guide sets out what each level means, and How to Sign Up for Heat-Health Alerts covers registration. Background on the agency is in The UK Health Security Agency: Alerts, Outbreak Advice and Local Teams, with wider material in the heatwaves and drought hub and the health emergencies hub. The toolkit also refers to cold weather, covered in Yellow, Amber and Red Cold-Health Alerts: What They Mean.
What happens next
The core alerting season runs to 30 September, with Heat-Health Planners issued every Monday and Friday throughout1. The toolkit, published on 28 May 2025 and first published in 2024, also records that the Flood Forecasting Centre launched the 2025 Rapid Flood Guidance Service, offering early warnings and preparedness advice1. No further dates for the 2025 season have been reported.
Sources (1)
- PHE document, humberandnorthyorkshire.icb.nhs.uk
UK Health Security Agency
Heat-Health Alerts Explained
Signing Up for Heat Alerts
