Heat related hazards

Heat and Heatwaves

Hot weather can affect anyone, but some people are more vulnerable to the effects of heat than others. During periods of hot weather or heatwaves, the risk of dehydration, heat exhaustion and heatstroke increases. Older adults, infants and young children, people with chronic medical conditions and those who work outdoors may be particularly affected.

In Ireland, a heatwave is generally defined as a period of five or more consecutive days with a maximum temperature over 25oC.

Heat-related illness

Heat exhaustion

Heat exhaustion occurs when the body becomes too hot and loses excessive amounts of water and salt through sweat.

Symptoms may include:

  • Headache
  • Dizziness or light-headedness
  • Excessive sweating
  • Muscle cramps
  • Nause or vomiting
  • Weakness or fatigue

Heatstroke

Heatstroke is a medical emergency that occurs when the body can no longer regulate its temperature.

Symptoms may include:

  • Confusion or unusual behaviour
  • Loss of consciousness
  • Seizures
  • Very high body temperature
  • Hot, dry skin
  • Being drowsy or difficult to wake
  • Little / no pee all day

If heatstroke is suspected, seek urgent medical attention.

For information on heat exhaustion and heatstroke in children: Heat exhaustion and heatstroke in children: symptoms, causes, prevention and treatments

For more information on heat exhaustion and heatstroke in adults: Heat exhaustion and heatstroke: symptoms, causes, prevention and treatments

Who is most at risk?

The effects of heat can be more severe for:

  • Older adults
  • Infants and young children
  • Pregnant women
  • People with heart, lung, kidney or other chronic medical conditions
  • People with dementia
  • People experiencing homelessness
  • People who work outdoors to undertake strenuous physical activity
  • People living alone
  • People living in poorly ventilated accommodation

Protect yourself during hot weather

Keep cool

  • Avoid spending long periods outdoors during the hottest part of the day (11am to 3pm)
  • Stay in the shade whenever possible
  • Wear light-coloured, loose-fitting clothes
  • Minimise unnecessary heating - turn off central heating, electrical equipment and lights that are not needed
  • Keep your home cool by closing curtains or blinds during the day and opening windows when temperatures are cooler in the evening and overnight
  • Dampening your skin with a wet cloth or wet towel may help to keep you cool

Stay hydrated

  • Drink water regularly throughout the day, even if you do not feel thirsty
  • Avoid alcoholic drinks, which can also cause dehydration
  • Check that older are drinking enough fluids
  • Aim for pale-coloured pee as a sign of good hydration
  • Parents and carers:
    • Babies and young children can become dehydrated quickly during hot weather.
    • Babies under 6 months should continue to receive breast milk or infant formula as their source of fluids.
    • Babies over 6 months can be offered water alongside their usual milk feeds and meals.
    • Encourage children to drink fluids throughout the day.
    • Eating fruits with high-water content (like watermelons, strawberries and melon) can be helpful, while ice lollies and jelly can be an occasional way of increasing fluid intake during hot weather.
  • Oral rehydration sachets may be helpful if you feel symptoms of dehydration – talk to your pharmacist about how best to use them

Stay sun safe

Check on others

Consider checking on relatives, neighbours and friends who may be more vulnerable to the effects of heat, particularly those who live alone or have underlying health conditions.

Additional resources

Heat Health Advice for Older Adults - Health Protection Surveillance Centre

Heat Health Advice for those with children - Health Protection Surveillance Centre

Heat Health Advice for Health and Care Professionals - Health Protection Surveillance Centre

Bathing Water - Health Protection Surveillance Centre

Drought leading to restricted water - Health Protection Surveillance Centre

Dehydration - Health Protection Surveillance Centre

Wildfires - Health Protection Surveillance Centre

For the latest weather updates and heat warnings: Met Éireann - The Irish Meteorological Service

For Child Safety advice in hot weather: Sun and outdoor safety for children

For Child Safety around water: Water safety for babies and children

For Water Safety: Water Safety - Department of Defence

For Sun Safety advice: How to be sun smart and protect your skin from the sun and sunbeds

Date updated: 22 June 2026