How much heat can a person safely endure? It depends. 

Much less visible and dramatic than hurricanes, floods and tornadoes, heat is considered the silent killer, affecting the lives and health of people across the country. An average of 702 heat-related deaths occur each year in the United States, according to  statistics from the Centers for Disease Control and Prevention (CDC). 

Certain groups of people should be especially careful during hot weather conditions. For example, city-dwellers and those living in the upper floors of tall buildings or in heat-prone regions are most at-risk for heat-related illness. People who have difficulty getting around or who have health conditions are particularly susceptible. The elderly and the very young also merit special attention during periods of high heat and humidity.

The National Oceanic and Atmospheric Administration's (NOAA) National Weather Service (NWS) and the Occupational Safety and Health Administration (OSHA) have also partnered to increase awareness for outdoor workers and their employers during excessive heat events. As part of this effort, NWS incorporates specific outdoor worker safety precautions when heat advisories and warnings are issued.

No matter what your job is or how you spend your free time, prevention of heat-related illness is key.

Here's what you can do:

Be informed and stay alert

Pay close attention to heat advisories or warnings that have been issued for your community.

• NWS continually updates heat-related advisories and warnings online at weather.gov. (Click on “Excessive Heat Warning” and “Heat Advisory” under the U.S. map — if there are no current warnings or advisories in the United States, nothing will appear).
• NOAA issues excessive heat warnings when weather conditions pose an imminent threat to life and heat advisories when weather conditions are expected to cause significant discomfort or inconvenience or — if caution is not taken — become life threatening.
• If you do not have internet access, you can get heat advisory and warning information by watching your local television or radio newscast or by purchasing a NOAA weather radio and tuning into NOAA Weather Radio All-Hazards.
• Use the temperature and humidity to figure out the heat index for your area, a measure that tells us how hot it feels.

Click here for more information on planning for periods of extreme heat, knowing what to do and not to do in extreme heat, and knowing the warning signs of heat-related illness.

Be prepared: Visit heat.gov today for comprehensive information on where heat is likely to hit and how to stay healthy during extreme heat. 

To see your heat risk, go to the National Weather Service’s experimental HeatRisk tool, a color-numeric-based index that provides a forecast risk of heat-related impacts to occur over a 24-hour period. HeatRisk takes into consideration:

• How unusual the heat is for the time of the year
• The duration of the heat including both daytime and nighttime temperatures
• If those temperatures pose an elevated risk of heat-related impacts based on data from the CDC

This index is supplementary to official NWS heat products and is meant to provide risk guidance for those decision makers and heat-sensitive populations who need to take actions at levels that may be below current NWS heat product levels.

Data is critical to providing information on how climate change affects Americans nationwide. Read more in the Commerce blog: The Importance of Data in Combatting Extreme Heat and Climate Change.