Heat-health Alert service

It is aimed at health and social care professionals and any with a role in reducing the harm extended periods of hot weather can have on health. The service covers England only.

Sign up for alerts 

The Heat-health alert service is provided by UK Health Security Agency (UKHSA) in partnership with the Met Office from June - Sept. It has been in operation since 2004 and is designed to help healthcare professionals manage through periods of extreme temperature. Should conditions for an alert be reached outside of this period, an extraordinary heat-health alert will be issued and stakeholders are advised to take the usual public health actions as recommended in the Adverse Weather and Health Plan.

In summer 2023, the Heat-Health Alerts transitioned to an impact-based alerting, which provides users with information over and above the fact that hot weather is likely to occur. It gives an indication of the impacts likely to be observed as a result of the temperatures. The Met Office regional daytime and night-time maximum temperature forecasts are monitored and when certain temperature thresholds are reached the Met Office and UKHSA undertake an assessment of the potential impacts and likelihood of those impacts occurring. Then a decision is made on whether an alert is needed, and if so, what type of alert to issue (YELLOW, AMBER or RED). 

The updated Heat-Health Alert system is more closely aligned with, and complementary to, the Met Office National Severe Weather Warning Service.

What the Heat-Health Alert colours mean:

Green (summer preparedness) - No alert will be issued as the conditions are likely to have minimal impact on health. However, during periods where the risk is minimal it is important that organisations ensure that they have plans in place and are prepared to respond should an alert (yellow, amber, or red) be issued.

Yellow (response) - These alerts cover a range of situations. Yellow alerts may be issued during periods of heat which would be unlikely to impact most people, but those you are particularly vulnerable (E.g. the elderly with multiple health conditions and on multiple medications) and are likely to struggle to cope and where action is required within the health and social care sector specifically. A yellow alert may also be issued if the confidence in the weather forecast is low, but there could be more significant impacts if the worst-case scenario is realised. In this situation the alert may be upgraded as the confidence in both the weather forecast and the likelihood of observing those impacts improves.

Amber (enhanced response) - An amber alert would represent a situation in which the expected impacts are likely to be felt across the whole health service, with potential for the whole population to be at risk and where other sectors apart from health may also start to observe impacts, indicating that a coordinated response is required. In addition, in some circumstances a National Severe Weather Warning Service (NSWWS) Extreme Heat warning may be issued in conjunction with and aligned to the HHA. This situation would indicate that significant impacts are expected across multiple sectors.

Red (emergency response) - A red alert would indicate significant risk to life for event the health population. A red warning would be issued in conjunction with and aligned to a red NSWWS Extreme Heat warning. Severe impacts would be expected across all sectors with a coordinated response essential.

A full overview of the new Heat-Health Alert system is available from UKHSA, and individuals can register to receive the alerts. 

The current alerting situation can be viewed on the new dedicated web platform. 

The Heat-Health Alerts and Cold-Health Alerts are part of the Weather-Health Alerting system which is operated by UKHSA in partnership with the Met Office and underpins the Adverse Weather and Health Plan. 

Hot weather guidance and advice to help professionals and the public address the risks of extreme heat to health are also available from UKHSA.