Before a heat wave learn the symptoms and how to recognize them

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Understand the symptoms and illnesses associated with extreme heat in order to stay safe as temperatures rise.

While heat can sometimes be dismissed as nothing more than an inconvenience, extreme heat is the most deadly weather event each year. To protect yourself and your loved ones when temperatures rise, learn how to recognize and prevent heat-related illness. 

Vulnerable populations

Everyone is at risk from the dangers of extreme heat. However, there are three key factors that put some people at higher risk than others:

  • Exposure: Some people are more exposed to high temperatures than others, such as people who work or exercise outdoors for long periods of time, homeless people, or those who do not have air conditioning.
  • Sensitivity: Infants, young children, pregnant women, older adults, and people with certain health conditions that are made worse by heat exposure, are less tolerant of heat than others. Certain medications can affect the body's ability to regulate temperature. Older people are also less likely to notice overheating, although physiologically they are at greater risk.
  • Ability to respond and prepare: Some people are less able to avoid heat than others, such as low-income populations who cannot afford air conditioning or the electricity to run it, people with mobility issues that prevent them from seeking medical attention or going to a cooling center during a heat wave, or people who work outdoors. Some people are less motivated to leave their homes and go to cooler places because they do not want to leave their pets behind, fear crime, or worry about being a burden to others.

Screen_Shot_2022-08-04_at_2.18.15_PM.pngClimate Change And Extreme Heat Guidebook

Recognize the symptoms

Extreme heat is especially dangerous because people might not recognize their symptoms as signs of a more serious condition. Symptoms like sweating or fatigue may just appear to be normal reactions to a hot day.  If untreated, heat-related illnesses can worsen and eventually lead to death. Therefore, It is important to know the symptoms of exposure to extreme heat and the appropriate responses. Warning signs and symptoms of heat-related illness, and recommended first aid steps are listed below.

Heat cramps

Heat cramps are muscle spasms, often in the abdomen, arms, or calves, caused by a large loss of salt and water in the body. Heat cramps can result from prolonged exposure to extreme heat combined with dehydration and often occur during strenuous outdoor activities such as physical labor or sports. Symptoms can include sharp, intense pain lasting anywhere from a few seconds to several minutes, extreme sweating, and flushed, red, or moist skinCramping is one of the mildest forms of heat illness and can be a good indicator that it’s time to take preventative action. First aid treatment includes:

  • Stopping activity for a few hours. 
  • Move to a cooler location
  • Remove excess clothing
  • Lightly stretch and gently massage affected muscles to relieve spasms  
  • Drink water, clear juice, or a sports beverage containing salt and sugar, such as Gatorade
  • Seek medical attention if cramps do not subside within one hour 

Heat exhaustion

During prolonged exposure to heat, your body begins losing the ability to regulate its core temperature. As your body becomes dehydrated the brain and heart can be affected due to poor blood flow (Source). The early stages of this process is known as heat exhaustion and are typically associated with heavy sweating, weakness, pale, cold, clammy skin, headache, dizziness, and an elevated, but weak or inconsistent heart rate. Heat exhaustion can occur from exposure to extreme heat over several days, especially when combined with dehydration. Heat exhaustion is a serious illness that requires emergency medical treatment. If you think you are experiencing heat exhaustion, it is important that you take steps to cool your body and avoid heat stroke. To prevent heat exhaustion and cool your body:

  • Move to an air-conditioned environment 
  • Lie down
  • Loosen clothing or change into lightweight clothing
  • Sip cool, non-alcoholic beverages (do not give liquids with caffeine or alcohol)
  • Take a cool shower or bath, or apply cool, wet cloths to as much of the body as possible

Seek medical attention if symptoms worsen or last longer than one hour, or if you have heart problems or high blood pressure.


Center for Construction Research and Training (CPWR) 

Heat stroke

Heat stroke is the most serious condition caused by extreme heat and requires emergency treatment. Heat stroke (or hyperthermia) occurs when the body cannot regulate its temperature and the temperature rises rapidly, causing widespread organ damage. Once your core body temperature exceeds 103°F (39.5°C) you will experience heat stroke. Typical symptoms include very high body temperature, no sweating, altered mental state, throbbing headache, confusion, nausea, dizziness, rapid pulse, and hot, dry skinIf someone you know is experiencing heat stroke get them to a shaded or cool area immediately and call 911 for emergency medical treatment. To reduce the severe symptoms associated with a heat stroke while waiting for medical attention:

  • Reduce body temperature with whatever methods you can: Cool cloths, a cool bath, or spray them with cool hose water. 
  • After administering cooling methods, move the person to a cooler place. 
  • Do not give liquids, there is a risk they will be unable to swallow and water may enter the lungs.
  • If there is uncontrollable muscle twitching, keep the victim safe, but do not place any objects in his or her mouth.
  •  If there is vomiting, turn the victim on his or her side to keep the airway open. 

Understand your risk of extreme heat

Extreme heat events can occur in any state. However, extreme heat is defined relative to the normal heat of an area, so extreme heat temperatures vary from region to region. Use Risk Factor to find property-specific heat risk assessments for any U.S. address.

If you live in a high-risk area, know where designated public shelters or cooling centers are located. To find the nearest shelter in your area text SHELTER and your ZIP code to 43362 (4FEMA). To find cooling-off centers enter your zip code at

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