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Heat-Health Alert

The Heat-Health Alert service is designed to help healthcare professionals manage through periods of extreme temperature. The service acts as an early warning system forewarning of periods of high temperatures, which may affect the health of the public.

The Heat-Health Alert service operates in England from 1 June to 15 September each year, in association with UK Health Security Agency (UKHSA). This is the period when temperature thresholds are most likely to be reached. However, should thresholds 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.

The Met Office forecasts day-time and night-time maximum temperatures, which are monitored regionally. When certain heat thresholds are passed, an alert is issued and sent to relevant health professionals and people working in social care as well as displayed on our website. This enables health professionals to take action to minimise the impact of the heat on people's health.

Sign up for alerts or contact our Health Team for more information.


What is a heatwave?

A heatwave is an extended period of hot weather relative to the expected conditions of the area at that time of year, which may be accompanied by high humidity.

A UK heatwave threshold is met when a location records a period of at least three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold. The threshold varies by UK county, see the UK temperature threshold map.

This is somewhat different to the Heat-Health Alert service, which is primarily for health and social care professionals and emergency planners to take preparatory action when conditions are potentially posing a significant threat to health. It has certain trigger thresholds depending on the region. UK Health Security Agency (UKHSA) provides a Heat-Health Alert service for England. The Heat-Health Alerts are part of that wider service, which is detailed in the multi-agency Heatwave Plan for England. The Heat-Health Alert service has five response levels (Level 0 – 4) based upon threshold maximum daytime and minimum night-time temperatures. Each alert level should trigger a series of actions which are detailed in the Heatwave Plan for England, from long-term planning out of season, to summer and heatwave preparedness and action, to a major national emergency. These thresholds vary by region, but an average threshold temperature is 30 °C by day and 15 °C overnight for at least two consecutive days.

  • Level zero: Long-term planning to reduce risk from heatwaves and includes year-round joint working to reduce the impact of climate change and ensure maximum adaptation to reduce harm from heatwaves.
  • Level one: This is in place every year from 1 June until 15 September, which is the period that Heat-Health Alerts are likely to be issued. This alert level simply means that people should be aware of what to do if the alert level is raised.
  • Level two: Issued when there is a high chance that the threshold will be exceeded within the next few days.
  • Level three: Issued when the Heat-Health Alert thresholds have been exceeded.
  • Level four: Issued when a prolonged hot spell becomes severe.

Where can I find the Heat-Health Alert webpage?

The Heat-Health Alert service is still available on the Met Office website but no longer appears as a banner on our home page. The service is for health professionals, contingency planners and emergency responders, and is used for planning purposes, with any alerts going directly to these groups. The public can keep up to date with the weather forecast on our website.

Why is hot weather an issue?

Many people enjoy hot weather but there can be serious health consequences from too much heat and vulnerable groups are particularly at-risk in prolonged hot spells.

What effect can a prolonged hot spell have?

Hot weather, especially when prolonged, with warm nights, can have effects on people's health and on certain infrastructure. To aid preparation and awareness before and during a prolonged hot spell, a Heatwave Plan for England has been created by UK Health Security Agency (UKHSA) in association with the Met Office and other partners. It recommends a series of steps to reduce the risks to health from prolonged exposure to severe heat for:

  • The NHS, local authorities, social care, and other public agencies
  • Professionals working with people at risk
  • Individuals, local communities and voluntary groups

Who provides the Heat-Health Alert service?

UK Health Security Agency (UKHSA) provides the Heat-Health Alert service, and issues health advice for the public and healthcare workers in England, according to levels of heat forecast/measured by the Met Office. It will also use its UV measuring capabilities to, when appropriate, issue public health advice about UV levels.

Relevant government agencies will work together in partnership to provide the best possible information and advice.

What is the difference between National Severe Weather Warnings and the Heat-Health Alert service?

National Severe Weather Warnings (NSWWS) are funded by UK Government and aimed at all sectors covering the whole of the UK. They are intended to warn the public and emergency responders of severe weather that has the potential to cause danger to life or widespread disruption. The Heat-Health Alert service is funded by UK Health Security Agency (UKHSA), aimed at the health sector, and covers England only. It is based solely on the health implications of hot weather, while the NSWWS cover the whole of the UK and includes the impacts of severe weather outside of the health sector.

Last updated: 18 May 2021