How to Survive a Heatwave

Survival Guru·August 26, 2026

A darkened room with drawn curtains, iced water, a damp cloth and a floor fan on a hot day

Heatwaves are the disaster nobody photographs. There is no wall of flame, no flooded street, no wreckage for the news — just a week of very hot days, and afterwards a body count that exceeds every other natural hazard in the country.

An analysis of Australian coronial records for 2001–2018 found at least 473 heat-related deaths reported to a coroner, 354 of them during heatwave conditions, and 244 of those indoors. Sixty-nine per cent of the fatalities were aged 60 or over, and among those who died indoors, 80% were in that age group — most of them in older housing. A recent nationwide analysis estimated around 1,009 deaths a year attributable to heatwaves.

Read that carefully, because it inverts the usual mental model. Heat does not mostly kill labourers on building sites or hikers in the sun. It mostly kills older people, indoors, at home, alone.

The 10-minute version

Shade the glass before the heat arrives. Curtains and blinds closed early in the morning on the sunny side does more than anything you can do at 3pm.
Cool the body, not just the room. Wet skin plus air movement sheds heat far faster than a fan alone. Cool showers, a wet shirt, a damp cloth at the neck.
Check on vulnerable people in person, twice a day. A phone call is not a check — heat confusion sounds fine on the phone.

Who is actually at risk

People over 60, by a wide margin, and disproportionately those living alone.
Anyone with a chronic condition — heart disease, respiratory illness, diabetes, kidney disease.
People on medications that affect fluid balance or sweating, including diuretics, some blood pressure medications, antidepressants and antipsychotics.
Babies and young children, who have less capacity to regulate.
Pregnant people.
People in older, poorly insulated housing, especially without working cooling.
Anyone without power, which is why heat and blackout is the dangerous combination — see How to Survive a Three-Day Blackout.

If you are in none of those groups, you are probably reading this for someone who is.

The day before

The preparation window is the day before, not the morning of.

Check the forecast for consecutive days. Three days above 35°C, or any day above 40°C, activates the plan. Sequences of hot days are more dangerous than single spikes, because houses do not shed the accumulated heat overnight.
Chill and freeze water. Bottles in the freezer become drinking water and cooling packs.
Charge everything, and know what happens if the power goes — heat drives demand and outages cluster on the hottest days.
Shop and cook now. You do not want to run an oven tomorrow.
Confirm your check-ins. Which vulnerable person are you visiting, and at what times.
Plan a cool destination. A library, a shopping centre, a cinema, a friend with aircon. Knowing where you will go removes the decision from the moment you are already unwell.

Cooling a house without air conditioning

Order matters here. Most people do these in the wrong sequence and get much less out of them.

1. Shade the glass, early. Close curtains and blinds on the sun-facing side before sunrise. External shading — awnings, shade cloth, even a sheet outside the glass — is dramatically better than internal, because it stops the heat before it enters.

2. Shut the house during the day. Windows and doors closed while it is hotter outside than inside. Opening up “for a breeze” at 2pm imports heat.

3. Open up at night, deliberately. Once the outside temperature drops below the inside, open windows on opposite sides and push air through with a fan. This is when you actually cool the structure, and it is the step most people skip.

4. Use fans on people, not rooms. A fan does not cool air; it moves it across skin. Point it at a person. Above roughly 35°C a fan alone can stop helping, and wetting the skin is what keeps it working.

5. Wet skin. Cool — not cold — showers, repeatedly. A wet shirt. A damp towel on the back of the neck, wrists and ankles. Cool water on skin is the single most effective non-mechanical cooling method available.

6. Retreat to one room. The lowest, most shaded, most southern room in the house. Cool one room properly rather than the whole house badly.

7. Turn off heat sources. Oven, dryer, unnecessary lights and electronics. Eat cold food.

8. Sleep low and light. Ground floor, minimal bedding, a damp sheet, a fan.

Hydration, and the thing people get wrong

Drink before you are thirsty. Thirst lags dehydration, and it lags further with age.

Water is the answer. Alcohol and large amounts of caffeine work against you. Very cold drinks are not better than cool ones. If someone is sweating heavily for hours, ordinary food covers the salt loss for most people — but if they are on fluid restrictions or diuretics, follow the medical advice they already have rather than pushing fluids.

Urine colour is the practical gauge. Pale is fine. Dark and infrequent means drink more.

When it becomes an emergency

The distinction between heat exhaustion and heat stroke matters, because one is managed at home and the other is a medical emergency. Full detail in Heat Stroke vs Heat Exhaustion.

Heat exhaustion: heavy sweating, pale clammy skin, weakness, dizziness, headache, nausea, muscle cramps. Move them somewhere cool, lie them down, cool the skin with water and air movement, sip fluids. It should improve within about 30 minutes.

Heat stroke — call 000 immediately: body temperature very high, confusion, slurred speech, unsteadiness, seizures or unconsciousness, and skin that may be hot and dry or still sweaty. Altered mental state is the sign that separates it, and it is a genuine emergency. While waiting: get them into shade or air conditioning, cool them aggressively with water, wet cloths and air movement, and do not give fluids to someone who is not fully alert.

The check-in that actually works

Most indoor heat deaths involve someone alone. The intervention is embarrassingly low-tech.

In person, twice a day, on every extreme day. Morning and late afternoon.
A phone call is not a check. Someone with heat confusion can hold a normal-sounding conversation. Go and look at them.
What to look at: is the house actually cool? Are they drinking? Is the cooling switched on and set correctly — every summer, someone is found with an air conditioner they were “saving” for later, or one set to heat.
Ask about medication. Some medications increase risk and some need refrigeration.
Agree a plan in advance: if the house cannot be kept cool, where do they go and who takes them.

That last one deserves emphasis. Older people frequently resist leaving, and resist running the aircon because of the bill. Both are worth pushing on, kindly and specifically.

What actually goes wrong

The house is opened up during the day for fresh air, importing heat.

Fans are used in an empty room, cooling nothing.

Nobody shades the windows until the sun is already on the glass.

Cooling is not run to save money. A genuine and common problem. Concessions and energy hardship programs exist; running the aircon for a week is cheaper than a hospital admission.

Consecutive days are underestimated. The third hot day is far more dangerous than the first, because the house never cooled overnight.

Check-ins are done by phone.

Heat and blackout are planned separately, when they arrive together.

Pets are forgotten. Water in the shade, brought inside, never left in a car.

Exercise happens at the usual time. Move it to early morning or skip it.

Thresholds

Situation	The rule
Forecast: 3 days above 35°C, or any day above 40°C	Activate the plan the day before
Morning of a hot day	Curtains and blinds closed on the sun side before sunrise
During the day	House shut. Fans pointed at people, not rooms
Above ~35°C indoors	A fan alone may stop helping. Wet the skin as well
House will not go below ~30°C	Leave. Library, shopping centre, cinema, a friend with power
Vulnerable person	In-person check twice daily, morning and late afternoon
Confusion, slurred speech, unsteadiness, collapse	000 immediately. Cool aggressively while waiting
Heat exhaustion not improving in 30 minutes	Escalate — call for medical advice

What it costs

Tier	Spend	What it buys
Free	$0	Closing curtains early, shutting the house by day and opening at night, cool showers, wet cloths, frozen water bottles, the in-person check-in, a cool destination chosen in advance
Solid	~$50–150	A pedestal or box fan, a cheap indoor thermometer, an esky and ice bricks, shade cloth for the worst window
Better	~$300–1,200	External blinds or awnings on the sun-facing side, ceiling fans, insulation top-ups — all of which cut the peak indoor temperature every summer thereafter
Energy bills	—	Check concessions and hardship programs rather than not running cooling. Running it is the cheaper outcome

The drill: the day-before hour

Ten minutes. Check the forecast for consecutive days. Decide if the plan is on.
Ten minutes. Fill and freeze bottles. Chill drinking water. Make sure there is cold food that needs no oven.
Ten minutes. Test the fans and the cooling. Confirm the aircon is on the right setting and the filters are not blocked.
Ten minutes. Identify your coolest room and clear it for use.
Ten minutes. Confirm your check-ins — who, when, and what you will look at.
Ten minutes. Decide the cool destination and how you would get there without a car if needed.

Frequently asked questions

How dangerous are heatwaves in Australia?

More dangerous than any other natural hazard by mortality. Coronial records for 2001–2018 identified at least 473 heat-related deaths, 354 during heatwaves and 244 of those indoors, with 69% aged 60 or over.

How do I cool a house without air conditioning?

Shade the glass before sunrise, keep the house shut while it is hotter outside, open up at night to flush the heat out, point fans at people rather than rooms, wet your skin repeatedly, and retreat to one low, shaded room.

Do fans actually help?

They help by moving air across skin, not by cooling air. Above about 35°C a fan alone may stop being effective, so wet the skin as well — a damp shirt or cloth plus airflow is far more effective than either alone.

What is the difference between heat exhaustion and heat stroke?

Heat exhaustion involves heavy sweating, weakness, dizziness and nausea and should improve within about 30 minutes of cooling. Heat stroke involves altered mental state — confusion, slurred speech, unsteadiness, collapse — and is a medical emergency. Call 000.

How often should I check on an elderly relative in a heatwave?

In person, twice a day, morning and late afternoon. A phone call is not sufficient, because someone with heat confusion can sound normal on the phone.

What if the house will not cool down?

Leave. A library, shopping centre, cinema or a friend’s place with working cooling is a legitimate plan, and deciding in advance where you would go removes the decision from a moment when you are already unwell.