With another major heat wave expected in the coming days, this time scorching the Rockies, while hotter-than-usual weather continues to affect other parts of the United States, millions of people are again bracing for blistering temperatures. Experts say it’s critical to have a plan for staying cool and safe, especially if you don’t have air conditioning.

“Air conditioning saves lives in these times of very extreme heat,” said Matthew Levy, an associate professor of emergency medicine at Johns Hopkins University School of Medicine. “Tragically, when we see people who succumb to heat-related illness or severe outcomes, it’s usually lack of access to air conditioning.”

But many homes aren’t outfitted with air conditioning, particularly in temperate climates such as the Pacific Northwest, where hundreds recently died during a historic heat wave. Meanwhile, people who do have air conditioning may be concerned about skyrocketing utility bills, overloading electrical grids or contributing to human-caused climate change, which is largely the driving force behind the frequency of extreme heat events.

If you’re trying to safely beat the blazing heat while living in a home without air conditioning, here’s what you need to know.

Frequently Asked Questions

  • When is it too hot for me to safely be in my home?
  • How can I effectively and safely use fans?
  • Will placing ice in front of a fan help?
  • Should I keep my windows open?
  • What else can I do to stay cool?

When is it too hot for me to safely be in my home?

Everyone tolerates hot weather differently. But people who have problems regulating their body temperature, such as the elderly, pregnant people, babies and children, and those with chronic or mental health conditions are among the most vulnerable to heat.

Experts recommend knowing and watching out for the symptoms of heat-related conditions, such as heat exhaustion and heat stroke, to gauge whether an environment is no longer safe. But, Levy said, if the temperature in your home starts to approach or exceeds 90 degrees, you should leave and find a place with air conditioning. When indoor temperatures reach the high 90s, electric fans won’t prevent against heat-related illness, according to the Centers for Disease Control and Prevention.

Ideally, if you don’t have air conditioning, you should be planning to go elsewhere long before temperatures reach 90 degrees, said Craig Crandall, a professor of internal medicine at the University of Texas Southwestern and a research scientist at Texas Health Presbyterian Hospital in Dallas.

“By you just staying in your apartment and waiting for it to get so hot that you have to leave, you’re essentially, in my opinion, playing at the edge of a cliff,” Crandall said, adding that it’s especially risky for those who are more vulnerable.

How can I effectively and safely use fans?

Remember that fans don’t cool air, they just move it around, said University of Oregon buildings scientist Alexandra Rempel. Having a fan blow air that is hotter than your body temperature can actually make it more difficult for your body to shed heat by sweating. Humidity will also affect your ability to sweat.

Crandall compared using a fan in a hot room to cooking a turkey in a convection oven. “Typically, it’s an oven with a fan that’s blowing the hot air on the turkey and the turkey cooks a lot faster,” he said. “It’s the same theory with humans that if you’ve got a fan blowing hot air around you, you’re going to cook, if you will, or your temperature is going to be up higher faster.”

But if the indoor air temperature is in the low 90s or below, turning on a fan can create an artificial breeze that helps evaporate sweat from your skin, making you feel cooler, Rempel said. Make sure any ceiling fans are spinning counterclockwise, so they push air down in a column. If you’re using a window fan, place it where it will draw in the coolest air — a fan in a window overlooking a leafy backyard is preferable to one that pulls in hot air and car exhaust from a busy roadway.

Position yourself so that you’re exposing large areas of skin to a fan’s breeze, said Robert Bean, a distinguished lecturer with the American Society of Heating, Refrigerating and Air-Conditioning Engineers. “It might feel better to have the air flow in your face, but that’s not removing the amount of stored heat that you’re retaining,” Bean said.

The effect of fans can be enhanced by adding water, experts said. Have a spray bottle handy and keep your skin moist by misting yourself often.

Will placing ice in front of a fan help?

A fan that blows air over ice can essentially create “a really low-cost little AC,” said Jin Wen, a professor in the Department of Civil, Architectural and Environmental Engineering at Drexel University.

While using ice and a fan might provide some personal relief, it’s not likely to cool the entire space and isn’t a long-term solution, said Wes Davis, technical services director of the Air Conditioning Contractors of America, a trade association. But for those who want to try it, Davis suggested adjusting the fan speed, if that’s an option, to a lower setting.

“It’s all about transferring heat, so if the air moving across [the ice] is moving very, very quickly, the time for heat transfer is reduced,” he said.

Should I keep my windows open?

Staying safe during a heat wave is all about managing the amount of energy that comes into your home, Rempel said.

During the day, when sunlight is beating down, you’ll want to keep your windows closed and covered. Because glass readily transmits heat, it’s most effective to have coverings on the exterior of the house, such as shutters or retractable awnings. If that’s not an option, you should close any interior curtains or blinds. And in a pinch, try covering a piece of cardboard in aluminum foil and pressing it into the window frame. The foil will reflect sunlight outward, keeping that energy out of your home.

Open up your windows as the outside temperature falls at night and through the early mornings, as long as security and noise won’t be an issue, Bean said. “Let the cool air from the outside blow through the house. … You want to remove the stored heat inside and get it outside, and the air becomes that mechanism to do that.”

But be mindful of the humidity levels, Wen said. “When indoor and outdoor temperature are not that different or outside is a couple degrees lower, but it’s much more humid, then I would say, don’t open a window.”

If you’re trying to cool down your home by bringing in air from outdoors, experts recommend creating cross ventilation by opening windows and doors on opposite sides of rooms. Strategically placed fans blowing hot air out and channeling cooler air in can help speed up the process, Bean said.

In homes with more than one story, make sure rising hot air can flow out through windows on upper floors or openings in the roof, Rempel said. This allows cool night air to flow through the home, removing heat energy that has accumulated in the very structure of the building.

What else can I do to stay cool?

Water is essential, Crandall said. “Drinking it and spraying it on your body, those are the best things that you can do when you don’t have air conditioning.”

Wear less clothing and choose loosefitting garments. Place ice packs or wet and, if possible, chilled towels or cloths on your body. It’s not generally recommended to sleep on wet bed linens. “They can become musty or moldy,” Levy said.

Take cool showers or baths, or fill up a kiddie pool, but be careful where you put it, Levy said. “Kiddie pools on terraces in high-rise buildings — not a good idea. People don’t realize that, but that’s a lot of weight to put on a balcony or terrace.”

Experts also suggested keeping activity levels low, especially during the hottest parts of the day. Try to limit or avoid using devices and appliances that generate heat, such as stoves, ovens and dryers.

Spend your time in the cooler areas of your home, said Krystal Pollitt, an environmental health studies professor at the Yale School of Public Health. During the day, steer clear of west-facing rooms with windows, and sleep in the basement or lower levels of your home.

To control humidity, consider buying a dehumidifier. Indoor humidity should be below 80 percent, Wen said, which “will help you to continuously sweat, and then that will take away your body heat.”

While all these cooling strategies may help, experts emphasized that they are only temporary fixes, and the safest thing to do in a relentless heat wave is to seek out air conditioning and make sure to help others in need. Even a few hours in an air-conditioned place, such as a library or shopping mall, can give your body an opportunity to recover, dramatically decreasing your chance of heat illness.

“Having a Plan B of another place to go if levels get to be too hot is imperative,” Pollitt said.