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Heat Illness and Heat Waves

Extreme Heat and Your Health

Hot and humid summer weather can cause heat illness and even death. More Americans die from heat waves than all other natural disasters combined. In New York City, more than 80% of heat stroke deaths in recent years involved victims who were exposed to heat in homes without air conditioning. Older adults, people with chronic medical conditions or mental health conditions, the socially isolated, and certain other groups are most vulnerable.

Check the Weather Reports

Pay attention to weather reports on the news, or check National Weather Service reports. The heat index is a measure of how hot it feels based on temperature and humidity. A heat index above 95°F is especially dangerous for older adults and other vulnerable individuals.

Keep Cool

The best way to prevent heat illness is to stay in an air conditioned place. Make sure you and your family stay cool during a heat wave. If you or someone you know cannot stay cool at home, visit a cool place like a library, a friend’s home with air conditioning, or a city cooling center. Cooling centers are open across the city during serious heat waves. To locate one, visit: Find a Cooling Center or call 311.

Check on Neighbors and Family Members

Check on vulnerable family, friends, and neighbors to make sure they stay safe and cool. Air conditioning is the best way to keep cool when it is hot outside, but some people do not have an air conditioner or do not turn it on when they need it. Encourage them to use air conditioning. Help them get to an air-conditioned place if they cannot stay cool at home.

What is Heat Illness?

Heat illness occurs when the body cannot cool down. The most serious forms of heat illness are heat exhaustion and heat stroke. Heat stroke occurs when the body’s temperature rises quickly, and can rapidly lead to death. Keeping cool can be hard work for the body. This extra stress on the body can also worsen other health conditions such as heart and lung disease.

What are the Signs of Heat Illness?

Signs of serious heat illness include:
  • Hot, dry skin OR cold, clammy skin
  • Confusion, hallucinations, disorientation
  • Unconscious or unresponsive
  • Nausea or vomiting
  • Trouble breathing
  • Rapid, strong pulse
  • Weakness
  • Dizziness
Call 911 or go to the emergency room right away if you or someone you know has these symptoms of heat illness.

Warning Signs of Heat Illness
  • Heavy sweating
  • Muscle cramps
  • Light headedness, feeling faint
  • Headache
  • Decreased energy
  • Loss of appetite, nausea
If you or someone you know has warning signs of heat illness, get to a cool place, remove extra clothes, and drink lots of water.

Who is Most Likely to Get Sick From the Heat?

People most likely to get sick from heat include people who:

  • Are aged 65 years or older
  • Have chronic medical conditions such as heart disease, diabetes, or obesity
  • Have mental health conditions such as dementia or schizophrenia
  • Take certain medications that affect the body’s cooling mechanisms — talk to your doctor for more information and advice
  • Use drugs or drink heavily
  • Are socially isolated, have limited mobility, or are unable to leave the house
Talk to your doctor about how to prevent heat illness during hot and humid weather. If you don't have a doctor, call 311 or TTY: 212-504-4115 to find a doctor or clinic nearby.

How Can You Prevent Heat Illness?

Use your air conditioner when you are home. Air conditioning can be a life saver. When it is hot outside, it can be even hotter inside!

If you do not have an air conditioner:

  • Go to a cool place like a library, museum, mall, a friend’s home with air conditioning, or a cooling center. To find a cooling center during a serious heat wave, call 311 or TTY: 212-504-4115 and ask “Where is the cooling center nearest to me?” Translation services are available.

  • In extreme heat, a fan alone may not provide enough cooling. If you use a fan, use it ONLY when the air conditioner is on or when the windows are open.


  • Close window shades or curtains to keep the sun out of your home.


  • Try not to use your stove and oven.


  • Take a cool shower or bath using tepid water. Sudden temperature changes may make you feel dizzy or sick.


  • Drink plenty of water on hot days, even if you are not thirsty


  • Avoid drinks with alcohol, caffeine, or lots of sugar
How Can You Prevent Heat Illness While Outdoors?

People who work or exercise outdoors are at risk of becoming dehydrated and developing heat-related illness.

  • Avoid strenuous physical activity
  • Drink plenty of water on hot days, even if you are not thirsty
  • Stay in the shade and out of direct sun
  • Wear light, loose-fitting clothes
  • Use a hat to protect your face and head
  • Wear sunscreen with at least an SPF of 15
  • Limit outdoor activities to early morning and late evening hours

  • Avoid drinks with alcohol, caffeine, or lots of sugar

What Can You Do To Protect Yourself From Heat Illness While Working Outdoors?
  • Drink water every 15 minutes
  • Take frequent rest breaks in shaded or air conditioned areas
  • Wear lightweight, light colored, loose-fitting clothing if possible
  • Be alert for the signs of heat illness in yourself and in your colleagues

For more information visit the Occupational Safety & Health Administration Heat Illness website.
General Resources

Resources for Healthcare Providers