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.
In this experimental 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.
This map shows the probability that the Average Heat Index (which takes into consideration temperature and humidity) will exceed a given value over for at least 2 days in the forecast window.
This map shows global tropical hazards predicted by NOAA for the upcoming two week period. Orange and blue coloring indicates the level of confidence that above or below normal temperatures, respectively, will develop in the forecast window.
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 that create a heat hazard include direct sunlight, low winds, high humidity, and high temperatures. When these conditions exist, a heat hazard is created.
Higher summertime temperatures are linked to an increased risk of illnesses and death, particularly among certain groups. Select a group below to learn more.
View heat warnings in your area by state
Familiarize yourself with these terms to help identify an extreme heat hazard:
The NIHHIS is an integrated system that builds understanding of the problem of extreme heat, defines demand for climate services that enhance societal resilience, develops science-based products and services from a sustained climate science research program, and improves capacity, communication, and societal understanding of the problem in order to reduce morbidity and mortality due to extreme heat. The NIHHIS is a jointly developed system by the Centers for Disease Control and Prevention (CDC) and the National Oceanic and Atmospheric Administration.