How to Stay Cool Without Power
In a hot-weather blackout, shade, water, the lowest room, and a named cooling-center backup matter more than a battery fan. CDC notes that indoor fans alone are not a reliable cooling method around 90°F and above. Ready.gov says water needs can double in very hot temperatures. If someone shows heat-stroke signs - confusion, faintness, a very high body temperature - call 911.
Arizona households feel this first. Maricopa County Department of Public Health reported 645 heat-associated deaths in 2023, a figure about heat in a normal powered summer, not about a blackout, and the reason the Arizona edition of 90 Days Without Power treats cooling as a first-line survival plan. The same physics apply in Texas, inland California, and anywhere an un-air-conditioned house can become dangerous in hours.
What to do in the house before you decide to leave
Close blinds on the sunny side, pick the lowest shadiest room, drink water before you feel thirsty, and reduce hard physical work in the heat.
Drawn shades, a low room, and water are the first moves while you decide whether the house is still safe. Night air can help in desert shoulder seasons; use cooler hours for heavier work. Do not run a generator or a car in an enclosed place to power a swamp cooler or an air conditioner. Evaporative coolers need electricity and relatively dry air; they are not a substitute for a leave plan if the power is out.
A car with fuel and working air conditioning is only a short-term cool-down option, never a sleeping space with the engine running in a closed garage or with a generator nearby. Carbon monoxide rules in the generator safety guide still apply.
When the house is no longer the plan
Write indoor-temperature triggers before a heat wave, and know how you will hear about official cooling centers (county public health, 211, or your state emergency information network).
Ready.gov tells people to check with local officials about cooling locations. In Arizona, AzEIN and county public health are the usual public sources; the Arizona edition of the book links them directly. City of Phoenix emergency-management kit guidance still starts with the one-gallon water baseline for at least three days, which is not enough for a desert two-week heat-plus-outage plan.
Heat stroke is a 911 emergency. Cool the person while you wait, and never give water to someone who is unconscious. The book's heat-illness chart is drawn from CDC-style warning signs.
Water math changes in the desert
If you use the heat factor, four people for 14 days need 112 gallons at two gallons each, not 56.
Use the water calculator and toggle extra heat. Store more than the several-day Ready.gov minimum if you live in a hot climate. Identify public cooling places that will also have water, and keep extra for pets.
Why a fan is not a plan once the house is around 90°F
CDC’s extreme-heat guidance has long warned that indoor fans alone are not a reliable way to cool people when temperatures reach around 90°F and above. Moving hot air over a dehydrated person can make the situation worse.
Fans help in milder indoor temperatures and can make shaded night air more comfortable when you can ventilate. They do not lower the body’s core temperature once the room itself is extremely hot. That is why this page puts water, shade, rest, and a named place to go ahead of a battery fan purchase.
Heat exhaustion and heat stroke are not the same. CDC describes heat stroke as a medical emergency involving a very high body temperature and changes such as confusion or loss of consciousness. Call 911. Move the person to a cooler place and cool them with whatever safe method you have while you wait. Do not give fluids to someone who is unconscious.
Older adults, young children, pregnant people, outdoor workers, and people with certain chronic illnesses are at higher risk in heat. So are people who take medicines that affect sweating or fluid balance; that is a pharmacist question, not a guess from a preparedness article. Check on neighbors who may not have a car or a person to call.
Maricopa County Department of Public Health reported 645 heat-associated deaths in 2023. That number describes heat in a county that still had electricity most of the time. It is included here as a documented reason Arizona households should treat a summer outage as a heat emergency first. It is not a blackout death count, and this page does not invent one.
Ready.gov’s heat and power-outage pages both mention cooling locations and extra water. City of Phoenix emergency-management household kit material still starts from the several-day, one-gallon idea, which is a starting line, not a July finish line. Use the water calculator with the heat box checked.
A desert household routine for a hot outage
Work and cook in the coolest hours, rest in the lowest shadiest room during the peak, drink water on a schedule, and leave when your written indoor-temperature trigger says so.
Close blinds and drapes on the sunny sides of the house. Interior rooms and lower floors usually stay cooler than west-facing upstairs bedrooms. A damp cloth on skin can help when the air is dry enough for evaporation; in very humid air that trick does less. Do not take chances with a generator-powered air conditioner placed where exhaust can enter the house. See generator safety.
Pets overheat too. Provide extra water and a cooler floor, and never leave animals in a closed car while you run an errand to a store that may also be without power. If you go to a cooling center, ask whether pets are allowed before you assume they are; policies vary by site and by city.
Write two backup locations: one nearby (a library, community center, or mall that officials have named, or a neighbor with a still-working generator and a safe exhaust setup) and one farther if you have fuel and a reason to travel. Do not drive through floodwater to chase air conditioning.
The Arizona edition of 90 Days Without Power adds AzEIN, county public-health cooling information, and the state’s heat reality to the general guide. Start at Arizona power outage preparedness. Other hot-climate states can use this same page plus their own state index entry.
What this page will not tell you to do
Do not sit in a closed garage with a car running for air conditioning, and do not place a generator next to a window to power a swamp cooler.
Those setups recreate the carbon monoxide deaths that CDC and CPSC already document around storms. A short drive with a working car air conditioner can help someone who is overheating, as long as the car is outdoors and the exhaust is not trapped. It is not a bedroom.
If someone in the home uses a powered medical device, heat plus an outage is a reason to talk with the clinician before summer, not during the first heat wave. The book’s medical chapter treats device backup as a written plan.
Questions people ask
Will a fan keep us safe in extreme heat?
CDC says indoor fans alone are not a reliable cooling method around 90°F and above. Focus on shade, water, rest, and a cooling-center backup.
How much extra water should we plan for in heat?
Ready.gov notes that water needs can double in very hot weather. Use the calculator’s extra-heat option.