Hot weather advice: mass gatherings and planning events
Health advice for those planning events and mass gatherings during periods of hot weather in England.
Applies to England
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Topic: climate-related hazards
Hazard: all climate-related hazards, heat
Who this guidance is for
The purpose of this document is to provide public health principles to support planning for events and mass gatherings which may occur during periods of hot weather. This guidance provides advice for those who commission or organise events on how to reduce the impact of hot weather.
Members of the public attending events are encouraged to review the ‘beat the heat’ resources. Event organisers are encouraged to promote these resources to attendees.
Main messages
Event organisers should ensure that they have plans in place for the safe management of events and mass gatherings and ensure information on safe behaviours is available for attendees during periods of hot weather. All staff should be familiar with this guidance and your local plans before 1 June each year.
Hot weather can cause some people to become unwell through dehydration, heat exhaustion and heatstroke, and it can exacerbate existing health conditions. You can reduce the impact of hot weather at events by:
- identifying hot weather as a potential risk in event risk assessments and ensuring plans are in place to reduce the impact of hot weather
- providing adequate drinking water throughout the event in line with potable water and food hygiene plans
- having a plan in place to increase shaded areas
- planning activities at times of the day when it is cooler such as the morning or evening and advising attendees to stay out of the sun at the hottest time of the day between 11am and 3pm
- ensuring good public communications on how to reduce the risk associated with hot weather during the event and ensuring plans are in place to make changes to the event should there be extremely hot weather forecast
About hot weather and health
Climate change is already causing warmer temperatures in the UK.
During severe hot weather, there is a risk that people can develop heat exhaustion, heatstroke and other heat-related illnesses. Hot weather can increase the risk of heart attack, stroke, lung problems and other diseases.
Older people and those with underlying medical conditions are particularly vulnerable to the effects of hot weather but, during extremely hot weather, such as in July 2022 when temperatures surpassed 40°C in England, fit and healthy people can also be affected.
Who is at risk
Large public events can increase exposure to heat and direct sunlight and may also make organisational responses more difficult.
Individual behaviours often change (for example, people may be reluctant to use the toilet facilities due to the long queues or lose their viewing position and so purposely reduce fluid intake).
There is a risk of increased alcohol or recreational drug consumption that can lead to dehydration and increased body heat. Physical activity, such as dancing, can worsen dehydration and increase body temperature. As a result, this can lead to heat-related illness, dehydration, collapse and even death.
Considerations to minimise the risk of hot weather
The following checklist can be used when planning large scale public events (mass gatherings). This should be used in conjunction with other more detailed planning advice (for example, Health and Safety Executive’s ‘Events Safety Guide’ and the Purple Guide).
Be prepared for hot weather
To prepare, you can:
- listen to the news and check the local weather forecast so that you know when hot weather is expected
- look out for advice on what to do if services such as power, water supplies and transport are likely to be affected
- check air pollution forecasts and advice – air pollution can become worse during hot weather and can cause problems for people with asthma and other breathing problems
- ensure first responders have adequate training and resources to manage heat-related impacts
- keep in mind that alcohol, and some prescription and recreational drugs can worsen the effect of heat
- position water stations, toilets, and health facilities in shade
- ensure all staff are familiar with this guidance and your local plans before 1 June each year
Ensure good public engagement and communication
Event communications should provide advice to attendees on how to keep well during hot weather. The ‘beat the heat’ guidance for members of the public provides practical advice on how to stay safe and well during periods of hot weather.
In addition to signposting attendees to this information, event organisers should consider the following:
- prepare advice on staying safe during hot weather that can be distributed in areas where attendees will congregate
- messaging could promote the use of sunscreen, increasing water intake, seeking shade, covering the head, and wearing loose light coloured clothing
- messaging could be via digital screens, announcements, and printed media
- consider distributing cooling aids such as bottled water, fans, and hats
Protect attendees from the sun and keep them cool
To protect attendees from hot weather you can:
- provide temporary shaded areas at event locations (umbrellas, tents) and consider positioning toilet and health facilities in shaded areas
- reduce the need to queue (efficient check-in, additional staffing, or staggered ticket entry)
- provide a water spray, mist area or spraying (showers, garden hose); consider water misters attached to high velocity fans
- make available a map of local public air-conditioned spaces where people can have respite from the heat (consider extending opening hours of these venues)
- divert strenuous activities for cooler days or cooler periods of the day and provide an alternative, less strenuous programme for hot days
- consider the availability of sunscreen, hats, and fans; attendees should also be encouraged and allowed to bring sunscreen into events
Take steps to reduce the risk of dehydration
Ensure an adequate supply of drinking water throughout the event – on hot days it is advisable to provide free drinking water. Consider distributing water bottles or water dispensers to encourage attendees to drink enough fluids. Ensure drinking water is well signposted and safe to drink.
Alcohol has a dehydrating effect on the body. Encourage attendees to choose alcohol-free options, or alternate alcoholic drinks with a glass of water.
Consider provision of cool water-rich foods such as salads or ice lollies and ensure that food is kept cool to reduce the risk of food poisoning.
Further resources and information
About the Heat-Health Alert System
In line with other weather warning systems in operation within England (and the UK), warnings will be issued when the weather conditions have the potential to impact the health and wellbeing of the population. The alerts will be given 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. These assessments are made in conjunction with the Met Office when adverse weather conditions are indicated within the forecast.
Yellow and amber alert assessments cover a range of potential impacts (for example, impacts on specific vulnerable groups such as rough sleepers, through to wider impacts on the general population) as well as the likelihood (low to high) of those impacts occurring. This additional information should aid making decisions about the appropriate level of response during an alert period.
Within the alert that is issued, the combination of impact and likelihood will be displayed within a risk matrix.
Once the decision is made to issue an alert (yellow, amber or red), these will be cascaded to those registered to receive the alerts and made available on the new dedicated web-platform.
Alerts will be issued with as much lead time to the event as is possible to allow users time to make their local assessments and to initiate all appropriate actions to reduce harm to health. Users should review every alert when issued to ensure they fully understand the potential impacts and how likely they are to occur.
Additional documents and resources
Health and Safety Executive’s ‘Events Safety Guide’
Adverse Weather and Health Plan
Weather-Health Alerting System: user guide