When it's Too Hot for a Fan

Heat waves are a leading cause of heat-related illness – and even death. Not all methods for keeping cool are effective during a heat wave. Using a fan can be more harmful than helpful when indoor air temperatures are hotter than your body temperature.

Should I use a fan?

When indoor air temperatures are cooler than about 95 °F:

Use a fan when outdoor air temperatures are cooler than indoor air temperatures. (Fans in windows can blow cooler air into a room from outside).

Fans do not cool the air, so air currents flowing over the body must be cooler than your body temperature to cool you down.

When indoor air temperatures are hotter than about 95 °F:

Fan use may cause your body to gain heat instead of lose it. On very hot, humid days, sweat evaporates off the skin slower than normal, and fans make it even more difficult for the body to lose heat by sweating. It’s important to stay hydrated and follow other tips to get cool.

It may be helpful to have an indoor thermometer or a thermostat with a temperature display to tell you the actual temperature inside your home. This is especially helpful if you are or care for an individual at higher risk for heat-related illness.

Check on your neighbors, friends, and family members who may be at higher risk of heat-related illness:

  • Babies, young children, and adults over age 65 who are often less able to regulate body temperature, cool down from sweating, and can get dehydrated more quickly than others.
  • People with mental or physical disabilities, or who are dependent on others for daily care.
  • People who have preexisting health conditions, especially those who have diabetes or heart disease, have experienced a previous heatstroke, or are overweight.
  • People who live alone or do not leave their homes daily.
  • People who live in upper-level or top floor apartments.
  • People without air conditioning.

How can I prevent heat-related illness?

  • Use an air conditioner.
  • If an air conditioner is not available, spend at least 2 hours in air conditioned places (shopping mall, library, cooling center, air-conditioned home of family/friend).
  • If you cannot leave your residence/building, spend more time on the lower levels where it may be cooler.
  • Close window blinds and curtains.
  • Drink plenty of cool nonalcoholic and caffeine-free liquids.
  • Close curtains and window coverings.
  • Take a cool shower or bath. Place cold, damp cloths over your head, neck, armpits and body. Wear light, loose clothing.
  • Limit strenuous physical activity.
  • Avoid using your stove/oven.