Extreme Heat

The definition of extreme heat can be different based on where you live..

The sun can expose us to ultraviolet radiation (UV) as well as potentially dangerous levels of heat.
It is important to protect children from both.
Visit our sun safety page for more information on UV radiation! 

What is extreme heat?

“Extreme heat” is defined by the Centers for Disease Control and Prevention (CDC) as “times when temperatures are substantially hotter and/or more humid than average for a location and date.” This means that extreme heat can be defined differently in New York City versus Phoenix, Arizona (where average temperatures usually are much higher compared to NYC). The National Weather Service defines a “heat wave” as “a period of abnormally hot weather generally lasting more than two days.”

Globally, there has been an increase in extreme heat days and heat waves. Climate change is a broad term that describes how an area’s average temperature and weather conditions are changing over time. NASA’s Climate Kids explains these terms. 

Shade, humidity, and a breeze can alter what the temperature feels like. This is why weather channels sometimes describe the “feels like” or “real feel” temperature – sometimes it can feel hotter or colder than what it says on the thermometer. If you exercise, you know that your body temperature also changes how you experience the outside temperature. 

Our bodies work best within a comfortable and constant temperature range. When our environment is hot, our bodies have ways to cool us off, like sweating. When it’s too hot or stays hot for too long, the methods that our bodies use to stay cool do not work as well. 

During the night, it usually cools down. This helps our bodies and homes cool off. As our weather patterns change, temperatures are also getting less cool at night, making it harder for people to handle heat waves. 

Too much heat in our environment can be dangerous. Heat-related illnesses are conditions that occur when the body gets too hot and cannot cool off properly. 

It is important to identify people who may be at higher risk for heat-related illness and to take steps to keep them safe.  Children have unique characteristics that make them more vulnerable to heat compared to adults. These include having more skin compared to their body size and more challenges keeping the body at a consistent temperature.1 They also must rely on adults to keep them cool and hydrated. Certain adults may also be at increased risk. Here is more information from the CDC on these factors: CDC’s Extreme Heat. 

Heat can also make air pollution worse which can cause negative health effects, particularly for sensitive groups. Children are especially impacted by heat and air pollution because they spend more time outside, breathe faster than adults, and are growing and developing. It is important to check the Air Quality Index (AQI) in your area, just like you would a weather forecast. The AQI provides details about air quality and potential impacts on sensitive groups, including children. It provides information about steps you can take when air pollution is high. 

Extreme heat can be particularly harmful for those with seasonal allergies or asthma. Extra heat during heat waves can increase ground-level ozone, which can make asthma worse.2 Asthma Inhalers (pumps) stored in extreme heat may not work as well and may dispense less than a full dose of medication.3 As we are seeing longer periods of warmer weather, this can make pollen seasons worse and longer.4 

Extreme heat can be harmful to pregnant people. During pregnancy, the body needs more water.  Dehydration can cause serious complications. Heat can increase the risk of preterm labor and low birth weight as well as high blood pressure in pregnant people. Here is more information from the CDC: Extreme Heat and Pregnancy.

There are different types of heat-related illness. Here are a few key ones:5,6 

  • Heat cramps are painful muscle cramps that occur during or after exercising in the heat. If you notice these, stop physical activity, and move to a cool place. Drinking electrolyte-containing beverages and fluids usually helps. 
  • Heat rash is seen frequently in infants and young children. It happens when sweat ducts are blocked leading to a red rash that can have red pimples or blisters. There is a higher risk of skin infections. If you notice this rash, stay in a cool, dry place. You can wear loose fitting clothing. If you are concerned about infection, talk with your pediatrician. 
  • Heat exhaustion occurs from excessive sweating and dehydration, and there may be a small rise in core body temperature. Signs and symptoms include dizziness, weakness, muscle cramps, nausea and/or vomiting, and fatigue. If this happens, move out of the heat and sun to a cool place, rehydrate, and use cold towels or ice packs to lower their body temperature. If you have concerns, talk with your pediatrician, or seek immediate care in an Emergency Department.
  • Heat stroke is the most serious heat-related illness; it is a medical emergency. This occurs when the body overheats to a point where it begins to shut down. If your child is confused or unresponsive or has a temperature over 103 degrees F, call 911 and seek immediate medical care.

Extreme heat events are expected to become more frequent across the United States, including New York.  Pay attention to weather updates to be aware of potential heat events. The National Weather Service issues Heat Warnings, Watches, Advisories, and Outlooks to inform community members on heat hazards in their area. 

These alerts are developed in collaboration with local partners and consider the normal weather and temperature of the area.7 However, they do not provide health-related guidance.  Create a plan that works for you and your family to stay safe during extreme heat. You can check out the sections below for more information.

The CDC developed a tool called HeatRisk that allows users to check the risk of heat hazards in their zip code. This tool also provides information on air quality which can be worsened by heat events. This tool shows users their risk for heat-related illness and tips for staying cool in hot weather.

Heat can also make air pollution worse which can cause negative health effects, particularly for sensitive groups. When you check your local HeatRisk, scroll down to view the Air Quality Index for your area.  

Preparation is key to beating the heat. Regular home maintenance can ensure that you and your family are prepared for heat events. Here are some things you can do:

  • Plant trees for shade 
  • Maintain your air conditioner by cleaning or replacing the filter every 1-2 months during the cooling season. Here is more information: Maintaining your Air Conditioner
  • Talk to your landlord about fixing or replacing a broken AC unit if it came with your apartment
  • Install window shades, curtains, or blinds to keep out the sun
  • If renovating, ensure your home is well-insulated as this will help it stay cooler 
  • Apply for a free air conditioner through the Home Energy Assistance Program (HEAP)
  • Enroll in Con Edison’s financial assistance program to receive a discount on your utility bills
  • Learn about if a Cool Roof is right for you. Green roofs use soil and vegetation as insulation and reflect more sunlight than regular roofs
  • Ensure that doors and windows have tight-fitting screens and, in apartments where children live, window guards

Create a plan to keep yourself and your family safe when temperatures rise. This can include things like: 

  • Check local news for health and safety forecasts and updates
  • Check on your neighbors and have your neighbors check on you
  • If you live in a place where there are frequent power outages or your air conditioning is not consistently working, identify a safe, cool place for your family to go during times when the temperatures are very high. Many states provide cooling centers, which are air-conditioned public places. Click here to see cooling centers for New York State. 
  • If you live in NYC, sign up for NotifyNYC to get the most up-to-date climate information.

Air-conditioning can save lives during times of extreme heat. During extreme heat, using a fan or opening windows may not be enough to keep cool, and many heat-related deaths occur in homes without air conditioning. Even just a few hours in an air-conditioned space can reduce heat strain on the body.

  • Limit time outside as much as you can
    • Avoid strenuous activity, especially during the sun’s peak hours: 10:00 AM to 4:00 PM. If you must do strenuous activity, do it during the coolest part of the day. 
    • Keep an eye on the weather forecast when planning outdoor activities
    • Make sure that kids come inside before they feel overheated
    • Take breaks during outdoor activities
  • Keep your home cool with passive cooling tips 
    • Keep windows closed and shades pulled during the day; keeping the sun out helps to keep the heat out
    • Close doors and windows to keep cold air inside when using air conditioning
    • Try not to use appliances that produce heat like stoves, dryers, and dishwashers, especially during the hottest parts of the day
    • If possible, spend more time on lower floors because heat travels upwards
  • If your home gets too hot, seek a cooler place
    • Libraries, shopping malls, museums and gyms can be great places for a cool retreat from the heat
    • See the resources section for more information on cooling centers in your area
  • Use water to cool off
    • Take a cool shower 
    • Tie a wet bandana around your head
    • Use lukewarm water to sponge bathe babies
    • Find a pool or water feature to play in
    • If you have a fan, air movement over wet skin cools you off faster 
    • Adults in NYC can request a fire hydrant spray cap from your local firehouse 

While it can be nice to enjoy warm, sunny weather, it can be unsafe to spend time outside during extreme heat events because of the heat and sun exposure. For more information on how to protect your child’s skin and eyes from the sun, visit our sun safety page.

Staying cool and hydrated is key to keeping safe during extreme heat. Children should be encouraged to drink water frequently. Drinking water can be made more fun by infusing it with lemon, berries, or mint or using fun cups or straws. Sugary drinks should be limited as these can increase dehydration.

Babies under six months old may require extra breastmilk or formula but should not drink water. Babies over six months old can be offered cool water in addition to normal feeds.8 Children ages one to three years old need about four cups of fluids per day, including water or milk. This increases for older kids to around five cups for four to eight-year-olds, and seven to eight cups for older children. 

The amount of fluid varies for each child and may need to be adjusted depending on levels of physical activity and environmental conditions like high heat and humidity. Even if it doesn’t seem that hot, heat-related illness is more likely to occur during play or vigorous activity. It can help to increase hydration in the days and hours before scheduled activity to prevent harmful health effects. 

Recognize the signs of dehydration which can differ based on the child’s age:

Infants:

  • Fewer wet diapers, with the typical range being from six to eight per day
  • Overly sleepy
  • Sunken soft spot (fontanelle) on the baby’s head
  • No tears when crying

Children:

  • Dry lips or sticky mouth
  • Less urination or dark-colored urine – urine should be very light yellow, almost clear
  • Sleepy and irritable
  • Flushed skin

Teens:

  • Dry lips or mouth
  • Lightheadedness
  • Cramps
  • Thirst
  • Dark or less urine
  • Headache
  • Rapid pulse
  • Flushed skin
  • Feeling excessively hot or cold

If you recognize these signs, move your child to a cooler place, stop any physical activity, and rehydrate your child with water or electrolyte-containing beverages. If symptoms persist or you are concerned, contact your pediatrician or go to the nearest Emergency Department.

Pregnant people are more prone to dehydration and heat-related illness. They should take extra precautions to stay safe from the heat including staying hydrated, limiting sun and heat exposure, and recognizing early signs of heat-related illness.

Children left in a hot car can die of heat stroke very quickly, even if it doesn’t seem that hot outside. Opening a window or air-conditioning doesn’t keep a car cool once it is turned off. Here is more information: Prevent Child Deaths in Hot Cars.9 

It can happen to anybody, especially when you’re tired, distracted, or deviating from your regular routine. It is important to create a routine to ensure your child isn’t trapped in a hot car. This can include things like:  

  • Check the back seat before locking your car and walking away
  • Keep your purse or keys in the back seat to ensure you always check before you leave
  • Check that your child has arrived safely if someone else is driving your child (e.g., the person providing childcare)
  • Leave your car locked to prevent a curious child from climbing in and getting trapped
  • Teach children that cars are not safe and discourage play inside the car

It is important to take immediate action if you see a child alone in a car. Always call 911, and if the child is unresponsive or in distress, take action to get the child out of the car. 

  Prescriptions for Prevention 

Featured Rxs – English:

Extreme Heat:  Babies, Children, Pregnancy, Athletes

Featured Rxs – Español:

Cuidados en los Días de Calor Extremo: Para Bebés, Para Niños, Durante el Embarazo, Para Atletas

National and Statewide Resources

Albany – Capital Region:

  • Albany County: HEAP

Buffalo:

Hudson Valley:

New York City:  

Rochester:

Syracuse:

  1. Uibel D, Sharma R, Piontkowski D, Sheffield PE, Clougherty JE. Association of ambient extreme heat with pediatric morbidity: a scoping review. Int J Biometeorol. Aug 2022;66(8):1683-1698. doi:10.1007/s00484-022-02310-5
  2. Ground-Level Ozone Basics. United States Environmental Protection Agency. Accessed November 19, 2024. https://www.epa.gov/ground-level-ozone-pollution/ground-level-ozone-basics
  3. Hoye WL, Mogalian EM, Myrdal PB. Effects of extreme temperatures on drug delivery of albuterol sulfate hydrofluoroalkane inhalation aerosols. Am J Health Syst Pharm. Nov 1 2005;62(21):2271-7. doi:10.2146/ajhp050067
  4. Pollen. United States Department of Health and Human Services. Accessed November 19, 2024. https://www.hhs.gov/climate-change-health-equity-environmental-justice/climate-change-health-equity/climate-health-outlook/pollen/index.html#:~:text=Our%20changing%20climate%20has%20caused,earlier%20and%20longer%20pollen%20seasons.
  5. Sorensen C, Hess J. Treatment and Prevention of Heat-Related Illness. N Engl J Med. Oct 13 2022;387(15):1404-1413. doi:10.1056/NEJMcp2210623
  6. Grubenhoff JA, du Ford K, Roosevelt GE. Heat-Related Illness. Clinical Pediatric Emergency Medicine. 2007/03/01/ 2007;8(1):59-64. doi:https://doi.org/10.1016/j.cpem.2007.02.006
  7. Heat Watch vs Warning. National Weather Service. Accessed November 19, 2024. https://www.weather.gov/safety/heat-ww
  8. Muth N. Recommended Drinks for Children Age 5 & Younger. American Academy of Pediatrics. Accessed November 19, 2024. https://www.healthychildren.org/English/healthy-living/nutrition/Pages/Recommended-Drinks-for-Young-Children-Ages-0-5.aspx
  9. Prevent Child Deaths in Hot Cars American Academy of Pediatrics. Accessed November 19, 2024. https://www.healthychildren.org/English/safety-prevention/on-the-go/Pages/Prevent-Child-Deaths-in-Hot-Cars.aspx




Updated: Sophia Milazzo; Emma Chang RN MPH; and Hannah Thompson MD MPH; February 2025.