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Heat-Health Watch

Our Heat Health Watch 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 UK public.

Our Heat Health Watch Service operates in England from 1 June to 15 September each year, in association with Public Health England.

The Met Office forecasts day-time and night-time maximum temperatures, which are monitored regionally. When certain heat thresholds are passed, a warning 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.

For more information please contact our Health Team.


What is a heatwave?

Although there is no official definition of a 'heatwave' in the UK, the term can be used to describe an extended period of hot weather relative to the expected conditions of the area at that time of year.

This is different to the heat-health watch service, which is for health professionals and emergency planners, and has certain trigger thresholds depending on the region. Public Health England provide a heat-health watch service for England. The heat-health watch system comprises four levels of response based upon threshold maximum daytime and minimum night-time temperatures. 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. These temperatures can have a significant effect on people's health if they last for at least two days and the night in between.

  • Level one: This is the minimum alert and 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 minimum alert 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 thresholds have been exceeded
  • Level four: Issued when a prolonged hot spell becomes severe

Why is the heat-health watch no longer on the Met Office website?

The heat-health watch 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 has been created by Public Health England 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 service?

Public Health England (PHE) provides the heat-health watch 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 Watch 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 Watch Service is funded by Public Health England (PHE), aimed at the health sector, and covers England only. It is based solely on temperature factors and their potential health impactions, while the NSWWS cover the whole of the UK and is based on the impacts of severe weather.

Last updated: 31 January 2017