Participating agencies:   ASPR.CDC.EPA.FEMA.NIOSH. NOAA. OSHA.SAMHSA
National Integrated
Heat Health
Information System
NIHHIS helps decision makers prepare for extreme heat events days, months, and years in the future.
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Heat warnings in your area

View heat warnings in your area by state

Staying safe during a heat wave

Key Safety Tips
Key Safety Tips
  • Drink plenty of water; even if you do not feel thirsty. Avoid drinks with caffeine. Persons who have epilepsy or heart, kidney, or liver disease; are on fluid-restricted diets; or have a problem with fluid retention should consult a doctor before increasing liquid intake.
  • Never leave children or pets alone in closed vehicles.
  • Check on family, friends, and neighbors who do not have air conditioning and who spend much of their time alone.
  • Check on your animals frequently to ensure that they are not suffering from the heat.
  • Go to a designated public shelter if your home loses power during periods of extreme heat. Stay on the lowest floor out of the sunshine if air conditioning is not available.
  • Check the weather/listen to NOAA Weather Radio for critical updates from the National Weather Service (NWS).

Safety Tips If You Have To Go Outside
Safety Tips If You Have To Go Outside
  • Avoid strenuous work during the warmest part of the day. Use a buddy system when working in extreme heat, and take frequent breaks.
  • Dress in loose-fitting, lightweight, and light-colored clothes that cover as much skin as possible. Avoid dark colors because they absorb the sun’s rays.
  • Protect face and head by wearing sunblock and a wide-brimmed hat.
  • Postpone outdoor games and activities.
  • Stay indoors as much as possible and limit exposure to the sun.

Additional Safety Tips
Additional Safety Tips
  • Eat well-balanced, light, and regular meals. Avoid using salt tablets unless directed to do so by a physician.
  • Limit intake of alcoholic beverages.
  • Avoid extreme temperature changes.
  • Consider spending the warmest part of the day in public buildings such as libraries, schools, movie theaters, shopping malls, and other community facilities. Circulating air can cool the body by increasing the perspiration rate of evaporation.
  • Download the FEMA App for heat advisories and safety tips.
  • Text SHELTER + your ZIP code to 43362 (4FEMA) to find the nearest shelter in your area (example: shelter 12345).

Safety Tips Before Extreme Heat Arrives
Safety Tips Before Extreme Heat Arrives
  • To begin preparing, you should build an emergency kit and make a family communications plan.
  • Know those in your neighborhood who are older, young, sick or overweight. They are more likely to become victims of excessive heat and may need help.
  • Be aware that people living in urban areas may be at greater risk from the effects of a prolonged heat wave than are people living in rural areas.
  • Get trained in first aid to learn how to treat heat-related emergencies.

Tips to Prepare Your Home
Tips to Prepare Your Home
  • Install window air conditioners snugly; insulate if necessary.
  • Check air-conditioning ducts for proper insulation.
  • Install temporary window reflectors (for use between windows and drapes), such as aluminum foil-covered cardboard, to reflect heat back outside.
  • Weather-strip doors and sills to keep cool air in.
  • Cover windows that receive morning or afternoon sun with drapes, shades, awnings, or louvers. (Outdoor awnings or louvers can reduce the heat that enters a home by up to 80 percent.)
  • Keep storm windows up all year.

Heat Related Terms
Heat Related Terms
    Familiarize yourself with these terms to help identify an extreme heat hazard:
  • Heat Wave - Prolonged period of excessive heat, often combined with excessive humidity.
  • Heat Index - A number in degrees Fahrenheit (F) that tells how hot it feels when relative humidity is added to the air temperature. Exposure to full sunshine can increase the heat index by 15 degrees.
  • Heat Cramps - Muscular pains and spasms due to heavy exertion. Although heat cramps are the least severe, they are often the first signal that the body is having trouble with the heat.
  • Heat Exhaustion - Typically occurs when people exercise heavily or work in a hot, humid place where body fluids are lost through heavy sweating. Blood flow to the skin increases, causing blood flow to decrease to the vital organs. This results in a form of mild shock. If not treated, the victim's condition will worsen. Body temperature will keep rising and the victim may suffer heat stroke.
  • Heat Stroke - A life-threatening condition. The victim's temperature control system, which produces sweating to cool the body, stops working. The body temperature can rise so high that brain damage and death may result if the body is not cooled quickly.
  • Sun Stroke - Another term for heat stroke.
  • Excessive Heat Watch - Conditions are favorable for an excessive heat event to meet or exceed local Excessive Heat Warning criteria in the next 24 to 72 hours.
  • Excessive Heat Warning - Heat Index values are forecast to meet or exceed locally defined warning criteria for at least 2 days (daytime highs=105-110° Fahrenheit).
  • Heat Advisory - Heat Index values are forecast to meet locally defined advisory criteria for 1 to 2 days (daytime highs=100-105° Fahrenheit).

Related Links
Online Shareables


Climate conditions such as high temperatures create a heat hazard. Exposure to this hazard, particularly if a person is sensitive and not well adapted, creates risk, and increases the likelihood of negative health outcomes.

Health Outcomes

Exposure to extreme heat can have many direct effects on human health (heat stroke, reduced labor productivity), as well as indirect effects (promoting air pollution and increasing asthma attacks, overloading power grids requiring rolling blackouts). Negative health outcomes occur if an individual is exposed to the hazard and has not sufficiently adapted to reduce sensitivity.


Inherent characteristics of a person that make them vulnerable to heat, such as preexisting conditions, age, or occupation. To understand how to protect these groups, see Populations of Concern


The ability of a person to take measures to reduce exposure and sensitivity - for example, avoiding outdoor activities during the day or wearing personal protective equipment (PPE) that is designed to mitigate heat buildup. When exposure is not preventable, adaptability can help reduce the impact of heat.


The extent to which an individual is exposed to extreme heat. Going outside on a hot, humid day and working in direct sunlight constitutes high exposure, while reducing exposure includes avoidance of these activities. Sometimes exposure is not preventable.

Climate conditions

Climate conditions that create a heat hazard include direct sunlight, low winds, high humidity, and high temperatures. When these conditions exist, a heat hazard is created.


Planning for a long-term reduction in heat-health risk requires understanding the health risk of extreme heat, and following an organized series of steps for reducing risk.
1 Explore the Problem
2 Assess Vulnerability
3 Investigate Options
4 Prioritize Action
5 Take Action
See overview of Steps to Heat Resilience in the Climate Resilience Toolkit

At-Risk Groups

Extreme heat affects everyone, but some populations may be exceptionally vulnerable. Read more about how these at-risk groups can adapt to extreme heat to reduce their risk.

NIHHIS Updates

Ready for summer heat? Study finds new primary driver of extreme Texas heat wavesThursday June 28, 2018

A team of scientists found that a strengthened change in ocean temperatures from west to east (or gradient) in the tropical Pacific during the preceding winter is the main driver of more frequent ...

Climate Resilience Toolkit Publishes New Case Study on Heat Illness Early Warning in the CarolinasFriday March 16, 2018

Residents of the Carolinas are familiar with hot summers, but in some areas excessive heat events bring a higher risk for heat-related illness—and even death. A new tool can help local communities ...

Protecting Outdoor Workers from Extreme HeatTuesday June 06, 2017

Many outdoor workers get uncomfortably warm during the hot days of summer. As employers are responsible for providing a safe workplace, they need to know when uncomfortable becomes unhealthy. ...



6-10 Day Temperature Probability Outlook

In this map, shaded areas show where average temperature has an increased chance of being warmer or cooler than usual. The darker the shading, the greater the chance for the indicated condition. White areas have equal chances for average temperatures that are below, near, or above the long-term average for the month.

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