Guides · Quick answers
How to stay cool without power
Losing air conditioning in a heat wave is a health problem, not a comfort problem. These are the methods that work without the grid, the signs that mean it is time to leave, and who to check on first.
By PowerLockdown EditorialUpdated November 1, 20267 min readHow we research
In this guide
- 01The short answer
- 02How to keep a house cool without power
- 03How to stay cool yourself
- 04Fans: when they help and when they do not
- 05How to stay cool without power at night
- 06Heat illness: the signs that mean act now
- 07Who to check on first
- 08How to cool a room without electricity: what does not work
- 09What to keep for a summer outage
- QFrequently asked questions
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The short answer
To stay cool without power, keep sun out by day with closed shades, open windows at night if it is cooler outside, wet your skin and sit in moving air, and drink water before you are thirsty. Do not rely on a fan as your main cooling (CDC). In extreme heat, go to a cooling center.
Ready.gov defines extreme heat as temperatures above 90°F for at least two to three days, with humidity making it feel hotter. The methods below are ranked by how much they help, then the warning signs that mean home cooling is no longer enough.
How to keep a house cool without power
By day: keep the heat out
- Close drapes, shades and blinds on sun-facing windows during the day. Ready.gov lists window coverings, window reflectors and weather-stripping as ways to keep heat out.
- Keep windows shut while it is hotter outside than in. Opening them at 3 p.m. lets the hottest air of the day in.
- Do not cook indoors. CDC's extreme heat guidance says to avoid using the stove or oven. Eat cold, light meals: NWS suggests fruit and salads.
- Retreat to the coolest room. That is usually the lowest floor, on the side away from the afternoon sun, since warm air rises.
- Shut doors to rooms you are not using so you are only trying to keep one space cool.
By night: flush the heat out
The Department of Energy describes night flushing: using cooler night air to cool the home and its thermal mass, which often keeps a house cool through much of the next day. DOE notes it works best in climates with cool nights and regular breezes, and should not be used when outdoor air quality is poor, for example during wildfire smoke.
- 01After sunset, when the outdoor temperature drops below indoor, open windows on opposite sides of the house to cross-ventilate.
- 02Open a low window on the breezy side and a high or upstairs window on the other. DOE explains that air enters low, absorbs heat, rises and exits high.
- 03If you have a battery fan, set it in a window blowing out to pull cooler air through the room.
- 04Close windows and shades in the morning before the outdoor temperature passes the indoor one, to hold the cool air in.
| Time | Windows | Shades | You |
|---|---|---|---|
| Morning | Close once outside warms past inside | Close on sunny sides | Do chores and errands now |
| Afternoon | Closed | Closed | Rest in the coolest room or a cooling center |
| Evening | Open once outside is cooler | Open | Cool shower, light dinner |
| Night | Open for cross-ventilation | Open | Sleep low in the house, in light clothing |
How to stay cool yourself
- Cool water on skin. Ready.gov, CDC and NWS all recommend cool showers or baths. Without running water, wet cloths on the neck, wrists and forehead, or a damp shirt, work by the same evaporation.
- Drink before you are thirsty. NWS advises plenty of water and non-alcoholic, decaffeinated fluids even without thirst. If you are on a fluid restriction, ask your doctor first.
- Dress light. Loose, lightweight, light-colored clothing (Ready.gov, NWS).
- Move strenuous work to the coolest part of the day (NWS).
- Stay out of direct sun. NWS notes sunburn reduces your body's ability to cool itself.
Fans: when they help and when they do not
A battery fan is the main cooling device most households can run without the grid, and it has limits. CDC's extreme heat guidance says do not rely on a fan as your primary cooling device during an extreme heat event, and its power outage guidance says not to rely solely on fans. Ready.gov says fans move air but do not lower body temperature or prevent heat illness.
Below that temperature, a fan aimed at damp skin is effective. Our best battery operated fan for a power outage page compares runtimes. A small fan draws little power, so a power bank or portable power station can run one for a long time.
How to stay cool without power at night
- Sleep on the lowest floor, ideally in a room that was shaded all day.
- Take a cool shower or sponge bath right before bed, and keep a spray bottle and damp cloth by the bed.
- Use a cotton sheet only. Sleep on top of it if needed.
- Run the fan in the window pulling night air in, not blowing on you, once the room is above 90°F.
- Keep water by the bed and drink during the night.
Heat illness: the signs that mean act now
| Heat exhaustion | Heat stroke | |
|---|---|---|
| Signs | Heavy sweating, paleness, muscle cramps, tiredness, weakness, fast or weak pulse, dizziness, headache, fainting, nausea, vomiting | Body temperature above 103°F; red, hot, dry skin with no sweat; rapid, strong pulse; dizziness, confusion or unconsciousness |
| Do this | Move to a cooler place, remove extra clothing, sip water or a sports drink | Call 911. Move to shade, remove outer clothing, apply cold wet cloths or ice to head, neck, armpits and groin |
| Escalate | Call a healthcare provider if symptoms worsen or last more than an hour | This is an emergency; do not wait |
CDC's power outage guidance warns that heat stroke can cause death or permanent disability if emergency care is not given. When the house is too hot to cool, leave it. Ready.gov points to cooling centers, libraries and shopping malls, and suggests calling your local health department to find cooling locations. During an outage, a community location that still has power is the safer place to be.
Who to check on first
NWS lists newborns, infants and young children, whose bodies heat up faster than adults'; older adults, especially those with chronic conditions, limited mobility or certain medications, or who live alone; people with chronic medical conditions; and pregnant women. CDC's heat guidance says to check on a friend or neighbor, and have someone do the same for you.
- Medicines. Some medicines are heat sensitive. FDA says insulin vials and cartridges can stay unrefrigerated between 59°F and 86°F for up to 28 days, and pump insulin exposed above 98.6°F should be discarded. An evaporative cooling wallet helps keep insulin pens in range; see the picks below.
- Cars. Never leave a person or pet in a closed car on a warm day (Ready.gov). NWS says dashboards and seats can reach 180°F to over 200°F, and cracking windows does not significantly slow the heating.
- Pets. Ready.gov: give outdoor pets plenty of cool water and shade, and keep them off hot asphalt and dark pavement, which can burn paws.
How to cool a room without electricity: what does not work
- Running a generator indoors for an AC unit. Generators run outdoors only, at least 20 feet from windows, doors and vents (CDC, CPSC). A closed, hot house with a generator nearby is a carbon monoxide risk; keep a battery CO alarm on.
- Sitting in a running car in a garage to use its air conditioning. CDC: never leave a motor running in an enclosed or partially enclosed space.
- A fan blowing on you in a 100°F room. It moves hot air; see the NWS warning above.
- Opening every window in the afternoon. It brings in the hottest air of the day.
What to keep for a summer outage
These existing research-based picks cover medicine, a fan's power supply and a phone link to cooling-center updates. Specs come from manufacturer pages; we do not test products. Fans themselves are compared on the battery fan page.
No. 1First aid and medical
FRIO Individual Cooling Wallet
Best for: Keeping an insulin pen cool without a fridge
- Holds one insulin pen, two 3 ml cartridges or three 1.5 ml cartridges
- Manufacturer: minimum continuous cool period of 45 hours
- Activated with cold water; recharges in under 5 minutes
- Inner wallet 18 × 6 cm
Tradeoffs
- Evaporative cooling, not refrigeration
- Frio states 18 to 26°C (64.4 to 78.8°F) inside for at least 45 hours at a constant 100°F, which is not fridge-cold
No. 2Power bank
Anker 737 Power Bank (PowerCore 24K)
Best for: High-capacity USB-C bank that can charge a laptop
- 24,000 mAh
- 140W max output
- 2× USB-C + 1× USB-A
- Smart digital display
- 630 g (22.22 oz)
Tradeoffs
- No solar input; recharge from wall or USB-C
- Heavy for a pocket
No. 3Power bank
Goal Zero Venture 35 Power Bank
Best for: Rugged, waterproof bank you can recharge from a solar panel
- 9,600 mAh / 35.52 Wh
- IP67 waterproof (1 m for 30 min, port door closed)
- USB-C PD 18W in/out plus USB-A out (15W)
- Solar recharge with Goal Zero Nomad 10 (about 6-12 hrs); USB-C about 3 hrs
- 50-lumen flashlight; 10.12 oz; operating range 32-113°F
Tradeoffs
- Small capacity for a whole household; Goal Zero says to recharge it every 3-6 months in storage
- 18W is too slow for most laptops; solar panel sold separately
No. 4Power station
Anker SOLIX C1000 Portable Power Station
Best for: Running a fridge, lights, phones and a CPAP through a one- or two-day outage
- 1,056 Wh capacity (up to 2,112 Wh with the matching expansion battery)
- 1,800 W continuous / 2,400 W surge AC output
- LiFePO4 battery chemistry
- 6 AC outlets
- 28.44 lb
Tradeoff
- At about 28 lb it is a carry-to-the-car unit, not a grab-and-go bag item.
For typical outage lengths, see how long power outages last. If a fan, a fridge and medicine all need power at once, run the numbers with the BackupPowerAI power station quiz.
Frequently asked questions
- How do you stay cool without electricity?
- Close shades on sunny windows during the day, open windows at night when it is cooler outside, take cool showers or use wet cloths, drink water before you are thirsty and wear loose, light-colored clothing (Ready.gov, NWS). If the house stays dangerously hot, go to a cooling center or another place with power.
- How do you keep a house cool without power?
- Keep heat out by day and flush it out by night. Close drapes and shades on sun-facing windows, do not use the oven, and keep windows closed while it is hotter outside. After sunset, open windows on opposite sides for cross-ventilation; DOE says night flushing can keep a home cool through much of the next day.
- Do fans help in a power outage heat wave?
- Fans help evaporate sweat but do not lower body temperature or prevent heat illness (Ready.gov), and CDC says not to rely on a fan as your main cooling. NWS says not to point a fan at yourself when the room is hotter than 90°F. Use fans to pull cool night air through the house instead.
- How do you stay cool without power at night?
- Sleep on the lowest floor in a room shaded during the day, open windows once it is cooler outside, take a cool shower before bed, keep a damp cloth and water nearby, and use only a light cotton sheet. If you have a battery fan, put it in a window to pull night air in.
- When should I leave my house in a heat wave without power?
- Leave for a cooling center or a place with power if anyone shows heat exhaustion signs that do not improve, if the house stays too hot to cool by any method here, or if someone at high risk lives with you. Signs of heat stroke, such as a body temperature above 103°F or confusion, mean call 911 (Ready.gov).
Sources
- Ready.gov (FEMA), Extreme Heat, updated July 16, 2026.
- National Weather Service (NOAA), During a Heat Wave, accessed November 1, 2026.
- CDC, What to Do to Protect Yourself During a Power Outage, August 26, 2026.
- CDC, National Center for Environmental Health, It's Hot Outside: Extreme Heat Door Hanger, May 1, 2024.
- U.S. Department of Energy, Building Science Education, Natural Ventilation and Cooling, accessed November 1, 2026.
- U.S. Food and Drug Administration, Information Regarding Insulin Storage and Switching Between Products in an Emergency, content current as of September 28, 2026.
- U.S. Consumer Product Safety Commission, Carbon Monoxide Information Center, accessed October 27, 2026.
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