Extreme Heat

Days with abnormally high temperatures are increasing, putting human health, ecosystems, and infrastructure at risk.

In the last 30 years, heat has been the leading cause of weather-related deaths in the United States. As our climate continues changing, more parts of the country are likely to see extreme heat days.

The increasing frequency and intensity of extreme heat events mean that more people will be exposed to conditions that can lead to illness or even death, particularly among vulnerable populations such as the elderly, outdoor workers, children, and low-income individuals.

The National Integrated Heat Health Information System (NIHHIS) offers authoritative information on extreme heat at  Heat.gov . NIHHIS builds understanding of the problem of extreme heat, and improves capacity, communication, and societal understanding of the problem in order to reduce morbidity and mortality due to extreme heat.


Maps

The federal government has extensive data resources that can be used at national, regional, and local levels to monitor excessive heat conditions and understand current and future trends. Here's a sampling of maps and data visualizations related to extreme heat.

Current conditions

Shading on this map shows areas forecast to reach temperatures of 80°F or above in the next 24 hours. It also highlights locations where the  National Weather Service  has issued a Heat Advisory, or an Excessive Heat Watch or Warning.

Click or tap the map to view maximum temperatures forecast for the day or details on active heat alerts.

Each month, NOAA's Climate Prediction Center produces an outlook showing forecaster's confidence in predictions for above, below, or near normal temperatures over the next month and the next season. Change the map to show or temperature outlooks.


Future projections: days over 90°F

In the coming decades, climate scientists expect the number of days with excessive heat to increase in most parts of the United States.

This map shows projections for the number of days per year when temperatures will reach 90°F or higher around the year 2050, based on a high-emissions scenario. For southern regions of the contiguous United States, the projections indicate around half of the 365 days each year will reach temperatures of 90°F or above.

Click or tap the map to explore future projections for hot days.

Another important aspect of extreme heat is warm nights: when the environment doesn't cool off at night, heat stress accumulates. View projections for average daily minimum temperatures, often called overnight lows, in the U.S. Climate Resilience Toolkit's  Climate Explorer .


Future projections: energy needed for cooling

Increases in temperature will come with increases in the amount of energy needed to cool homes and businesses.

 Cooling Degree Days  are used to estimate the amount of energy required for cooling during hot months. Annual totals for cooling degree days represent the number of degrees above 65°F for each day, summed over the entire year.

Click or tap the map to see projections for cooling degree days around 2050, based on a high-emissions scenario.



Resources to explore

Here's a selection of federal resources related to extreme heat.