How to stay cool without power in a heat wave
The CDC says to go to an air-conditioned shelter, mall or library, or take cool showers or baths, and to drink plenty of fluids. At home, cover sunny windows with shades (EPA), and only use a fan if the room is below 90°F, because the CDC says above that a fan can raise your body temperature.
In heat stroke, body temperature can rise to 106°F or higher within 10 to 15 minutes, and the CDC says it can kill or cause permanent disability without emergency care.
- Keep the heat out of the house
- Keep your body cool
- The 90°F fan rule
- Get somewhere cool
- Heat exhaustion or heat stroke?
- Carbon monoxide warning
- Running a fan or AC on a generator
- Gear
Keep the heat out of the house
- Shade the sunny windows. Cover windows that get morning and afternoon sun. Outdoor awnings block more heat than indoor shades (EPA).
- Open or close windows by the outside air. If the air outside is cooler, open the shades and windows. If it is hotter, keep them closed (EPA).
- Use fans to move air, not to blast yourself. Use them to push hot air out of a room or pull cooler air in (NWS). Do not run a fan in a closed room (EPA).
- Do not cook indoors if you can avoid it (EPA). Eat light, cool food such as fruit or salads (NWS).
Keep your body cool
- Cool showers or baths (CDC). Wet your skin (Ready.gov).
- Drink plenty of water even if you are not thirsty. Avoid alcohol and caffeine (NWS). Light yellow or clear urine usually means you are drinking enough (CDC).
- Light, loose, light-colored clothes (NWS).
- Move less. Put off hard work until the coolest time of day (NWS).
The 90°F fan rule
A fan does not cool the air. It helps sweat dry off your skin (EPA). The CDC says use fans only when the indoor temperature is below 90°F. Above that, a fan can raise your body temperature. The NWS says the same: do not point a fan at yourself when the room is hotter than 90°F.
Get somewhere cool
- Find a cooling center by dialing 2-1-1 or calling your local health department (CDC).
- Malls and libraries count. Spend as much time as you can in air conditioning (NWS, EPA).
- Check on older, sick or frail neighbors (NWS).
- Never leave a child in a car, even with the windows down, even for a minute. The NWS says cracked windows do not slow the heating much.
Heat exhaustion or heat stroke?
| Heat exhaustion | Heat stroke | |
|---|---|---|
| Signs | Heavy sweating, weakness, cool pale clammy skin, fast weak pulse, muscle cramps | Throbbing headache, confusion, slurred speech, nausea, dizziness, body temperature above 103°F |
| Do this | Move to somewhere cooler, loosen clothes, cool wet cloths, small sips of water | Call 911. Move to somewhere cooler, cool with wet cloths or a bath. Do not give fluids. |
| Get help if | They vomit, or it gets worse or lasts longer than 1 hour | Always. Delay can be fatal. |
From the National Weather Service. The CDC counted an average of 702 heat-related deaths a year in the US from 2004 to 2018.
Carbon monoxide warning
If you run a generator to power fans, a fridge or a window air conditioner, the generator is now the biggest danger in your home.
The CDC says more than 400 Americans die every year from accidental carbon monoxide poisoning not linked to fires, more than 100,000 go to the emergency room, and more than 14,000 end up in the hospital. You cannot see or smell the gas. People who are asleep or drunk can die before they ever feel sick.
- Never run a generator, grill, camp stove or charcoal inside your home, basement or garage, even with the doors and windows open (CDC).
- Run generators outside, more than 20 feet from windows, doors and vents (CDC). Not on a porch or in a carport (CPSC).
- Never heat your home with a gas oven (CDC).
- Have a battery-powered or battery backup carbon monoxide alarm on every level and outside sleeping areas, and test it monthly (CPSC).
- Headache, dizziness, weakness, upset stomach, vomiting, chest pain or confusion can mean carbon monoxide poisoning (CDC). If the alarm sounds or anyone feels this way, get everyone outside, then call 911 or Poison Control at 1-800-222-1222.
Read the full rules on portable generator safety.
Running a fan or AC on a generator
Honda lists a 10,000 BTU window air conditioner at about 1,500 running watts and 2,200 starting watts (Honda wattage guide). Work out what yours can carry on what size generator do I need, and follow portable generator safety every time.
Common mistakes
- Pointing a fan at yourself in a room above 90°F. The CDC says it can raise your body temperature.
- Opening every window in the afternoon when the air outside is hotter than inside.
- Waiting to feel thirsty before drinking.
- Giving water to someone with heat stroke symptoms instead of calling 911.
- Leaving a child or pet in a parked car with the windows cracked.
- Running the generator in the garage to keep the AC going.
Gear for this
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Battery-powered fan
Moves air without the grid. Follow the CDC 90°F rule.
Blackout or reflective window shades
The EPA says shading sunny windows limits the rise in indoor temperature.
Indoor thermometer
You need to know when the room passes 90°F, the point the CDC says fans stop helping.
Battery-powered carbon monoxide alarm
Needed if you run a generator. The CPSC says have one on every level.
Questions people ask
How do you stay cool when the power is out?
The CDC says go to an air-conditioned shelter, mall or library, or take cool showers or baths, and drink plenty of fluids. Shade sunny windows and keep them shut when it is hotter outside, says the EPA.
Do fans help in a heat wave?
Only up to a point. The CDC says use fans only when the indoor temperature is below 90°F. Above that, a fan can raise your body temperature.
What are the signs of heat stroke?
The National Weather Service lists a throbbing headache, confusion, slurred speech, nausea, dizziness and a body temperature above 103°F. Call 911 straight away.
Sources
- CDC: What to Do to Protect Yourself During a Power Outage
- CDC: About Heat and Your Health
- CDC MMWR: Heat-Related Deaths, United States, 2004 to 2018
- National Weather Service: During a Heat Wave
- National Weather Service: Heat Illness
- EPA: Extreme Heat and Indoor Air Quality
- FEMA Ready.gov: Be Prepared for a Power Outage (PDF)
- CDC: Carbon Monoxide Poisoning Basics
- Honda: Generator Wattage Estimation Guide
Related entries
- P-02What to do when the power goes outThe first steps, food and medicine rules, and the carbon monoxide mistakes that kill people in outages.
- P-01Portable generator safety: where to put it and how not to dieOutside only, more than 20 feet from the house, never in the garage.
- P-06What size generator do I need? (simple worked example)Add up the running watts, add the biggest starting watts, done. A worked example with a fridge, sump pump and furnace fan.
- P-03How to stay warm without powerClose off rooms, block drafts, layer up, and never heat with a gas oven or grill.
General safety information only, not medical or professional advice. Rules can change, so check the linked sources and follow your local officials. As an Amazon Associate I earn from qualifying purchases.