Heat and heat waves

The Be Summer Ready campaign covers a range of information relevant to issues which may affect people during the summer months.

Definitions associated with heat-related climatological events can be found on the Met Éireann website. While there is no global definition for heatwaves, in an Irish context they occur when the daily maximum shaded air temperature is greater than twenty-five degrees Celsius for five or more consecutive days.

High temperature warnings are issued by Met Éireann for issues including health considerations, transport and infrastructure impacts, forest fires, and droughts. These warnings are basis for proactive action by a range of stakeholders with roles to play in minimising the health impacts of heat.

Heat and health

The impacts of heat on population health can be divided into three categories, the likelihood of which would be indicated by the issuing by Met Éireann of a high temperature (yellow / orange / red) warning. In addition, there may be regional, urban/rural or other variations across the country in relation to the severity of a heatwave. Accordingly, the following should be used as a general guide, and there may be instances where public health effects of heat may arise outside the classification applied by Met Éireann. Nonetheless, the following categorisation is intended as a guide to inform the type of advice and action which may be appropriate.

Category 1 (Minor) heatwaves

Heatwaves falling under category 1 can be considered minor in terms of duration and/or heat, meaning that their impacts on population health will generally be limited to the most vulnerable members of society.

Category 2 Heatwaves

The main focus of information to be provided to the general public relates to this category of heatwave. These heatwaves can have a range of effects across society, including in relation to water safety, fire risks and exposure to high UV level; this guidance document focuses on the health impacts of category 2 heatwaves and the information to be provided under the Health Preparedness subpage on the Be Summer Ready website.

Guidance note

This guidance note focuses on Category 2 heatwaves and on the information to be provided to the public on the Be Summer Ready website.

During a particular high temperature event in Ireland, a range of actors or agencies may provide their own tailored responses to heat waves. As a generic guide, the advice in this Guidance document is intended represent good practice and should be considered for inclusion in specific tailored advice as appropriate. As the frequency and severity of these events may increase in the coming years, authors of such guidance should seek to ensure that the information on the Be Summer Ready website is kept up to date.

Who is vulnerable to the health impacts of heatwaves

While the impacts of heatwaves should be borne in mind by all cohorts of society, the following are particularly vulnerable:

older people – especially those over 65 years of age
babies and children under 5 years of age
those who live on their own, and who may not be able to care for themselves, or are socially isolated
those living in a residential care facility
people who have a serious or long-term health condition including heart, lung or kidney disease, diabetes, peripheral vascular disease, obesity, Parkinson’s disease, or some mental health conditions
people taking medications that affect heart or kidney function, their ability to sweat, or their cognition or behaviour. Those with behavioural limitations, such as people with cognitive impairment (dementia/Alzheimer’s), restricted mobility, or those with drug and/or alcohol addictions
those who are bed-bound, and those dependent on others for routine activities
people with heightened exposure to heat, such as those who are experiencing homelessness and/or sleeping rough, people living in a top floor flat, those with outdoor occupations/activities

How you can stay cool

minimise unnecessary heating - turn off central heating, electrical equipment and lights that are not needed
keep out the sun between 11am to 3pm- stay in the shade or cover windows exposed to direct sunlight
if you have to go outdoors, protect your skin by using shade, wear clothing that covers the skin, a wide brimmed hat, sunglasses and sunscreen of 30+ for adults and 50+ for children
use natural ventilation such as open windows when the air feels cooler outside than inside (for example, at night) and where it is safe, secure and feasible to do so
increase air flow through buildings wherever possible
evaporative cooling – dampening your skin may help keep you cool
if you are using air conditioning, make sure it is using a fresh air supply, which is important to prevent spread of airborne illnesses such as COVID-19
electric fans need to be used with caution, as they may not be safe for higher temperatures and should not be used where a person may be incubating or suffering from illnesses such as COVID-19. If in doubt, seek medical advice

How you can stay hydrated

make sure you have enough water to drink
an adult needs approximately 2 litres of water over 24 hours. This may be less for smaller people or those with medical conditions
drink more fluids when you feel any dehydration symptoms. The best fluids to drink are water or oral rehydration sachets – chat to your pharmacist about how to use these safely
drink enough during the day so your urine is a pale clear colour

Advice for carers

The main issues to be aware of relate to maintaining the body temperature of the person you are caring for and ensuring that they stay hydrated. To help them:

make sure they drink during mealtimes
make drinking a social thing, like "having a cup of tea"

offer them food with a high water content – for example, ice cream or jellies, or fruits like melon.

Category 3 (Extreme) Heatwaves

Some heatwaves, owing to either a particularly high average temperature or to the duration of the heatwave, may be considered to fall into the category of national emergency. It should be noted that heatwaves associated with a Met Éireann Red High Temperature Warning have never occurred to date in an Irish context.

The Office of Emergency Planning oversees the Strategic Emergency Management National Structures and Framework, which details the Lead Government Department roles in Major Emergencies. The Framework for Major Emergency Management issued by the Department of Housing, Local Government and Heritage details how the three Principal Response Agencies, the Local Authority, An Garda Síochána and the Health Service Executive plan and prepare for the delivery of a coordinated responses to major emergencies. Information for the public and the sectors involved will be tailored to address specific emergencies, and may include particular regional considerations.