Hot weather in Australia is often an excuse to hit the beach or run through the sprinkler. Sounds fun, but persistent soaring temperatures can lead to illnesses such as dehydration and even heatstroke.

Here’s what you need to know about heat-related illness and how to stay safe during a heatwave.

Heatstroke is no joke

Heat can kill. Between 1844 and 2010, more than 5,330 people died from extreme heat events in Australia, according to the journal Environmental Science & Policy. In 2009 alone, there were 432 heat-related deaths in SA and Vic during a heatwave that caused catastrophic bushfires.

Interestingly, most heat-related deaths have occurred on January 27 — the day after Australia Day.

Hot weather can cause heatstroke, a life-threatening condition in which a person can no longer regulate their own body temperature. Normal body temperature is between 36°C and 37°C, but when a person experiences heatstroke, it can rise to above 40.5°C. If left untreated, heatstroke can lead to complications, such as organ failure, brain damage and death.

Dehydration and heat exhaustion, while less serious, are also examples of heat-related illness.

Read more about the signs and symptoms of heatstroke here.

Who’s most at risk during a heatwave?

While some people just complain a lot or gorge on ice cream, heatwaves can make others seriously ill.

The body usually cools itself down by sweating. When the weather is very hot, your body works even harder to produce sweat. If a person is dehydrated or unable to produce enough sweat, their temperature can rise rapidly.

Certain people are more at risk of this. Elderly people, for example, are less able to produce sweat, while young children produce more body heat, sweat less and have faster rising body temperatures.

The following groups are more likely to experience heat-related illness such as heatstroke:

• elderly people aged over 75 years
• babies and young children
• women who are pregnant or breastfeeding
• people with a chronic illness, such as heart disease,diabetes, kidney disease, cancer, dementia, alcoholism, mental illness or high blood pressure
• people with an acute illness such as an infection with a fever or gastroenteritis
• people who are obese
• people who are taking certain prescription medicines (talk to your GP about this)
• people who are socially isolated or homeless

If this sounds like you, keep your body cool, keep your home cool (close windows, shut curtains and blinds, use air-conditioning if you have it) drink plenty of water and call a friend or relative if you need help.

If you’re not at risk yourself, help others — visit or phone friends, family and neighbours who are more vulnerable. Keep children cool and give them plenty of fluids. Ensure pets have access to water and shade. And never leave babies, children or animals alone in a car.

How to keep cool during a heatwave

• Drink heaps of water — and check the colour of your wee. If it’s pale, you’re drinking enough; if it’s dark yellow, you need to drink more.

• Avoid alcohol, tea and coffee as they can make dehydration worse.

• On very hot days, avoid being outdoors between 11am and 5pm.

• At home, you can put wet towels or cool packs on your arms or neck or put your feet in cool water.

• If you don’t have air-conditioning, visit a cool place like a library, shopping centre or cinema.

• Figure out which room in your house is the coolest (this will often be on the ground floor on the south side).

• Use your stove and oven as little as possible.

• Keep an eye on the weather forecast.

Where to seek help

• If you become very unwell, contact your doctor or go to the nearest hospital emergency department. If you think your symptoms are serious, call triple zero (000) and ask for an ambulance immediately.
• You can call healthdirect on 1800 022 222 to talk to a registered nurse 24 hours a day, 7 days a week (known as NURSE-ON-CALL in Victoria), or use the healthdirect Symptom Checker.
• You can read more about hot weather risks here and looking after babies in hot weather here.

Watch this video from the Victorian Government's Department of Health and Human Services to learn more about extreme heat.