Dangerous heat levels are forecast for many parts of the contiguous United States on Sunday, according to data from the National Oceanic and Atmospheric Administration. Here is the latest.
Caution
Feel 80°-90°
extreme caution
90°-103°
Danger
103°-124°
Heat index forecast for Sunday
A map showing the highest predicted heat index level in the contiguous United States on Sunday.
CALIF.
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New York
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South Dakota
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NM
New York
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n/a
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South Dakota
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VERMONT.
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n/a
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TO THE.
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OF THE.
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New Jersey
NM
New York
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n/a
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OK SO.
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CS
South Dakota
TENNESSEE.
UTAH
VERMONT.
VIRGINIA.
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W.VA.
WIS.
WYO.
Source: NOAA
The map shows the highest predicted heat index level on Sunday.
About 30.4 million people — 9% of the population of the contiguous United States — live in areas where dangerous levels of heat are expected.
The heat index is a measure of the heat felt outdoors, taking into account humidity and temperature. The measurement is used to indicate when the level of heat is dangerous for the human body in the shade. When exposed to the sun, a person can perceive this temperature to be up to 15 degrees Fahrenheit (8.3 degrees Celsius) higher.
Risks Associated with Heat Index Levels
Caution
Fatigue is possible after long exposure or exercise.
A heat index of 80 to 90 degrees Fahrenheit
extreme caution
Possible risk of heat stroke, heat cramps or heat exhaustion after long exposure or physical exercise.
90 to 103 degrees
Danger
Heat cramps or heat exhaustion are likely. After long exposure or physical exercise, heat stroke is also possible.
103 to 124 degrees
Extreme danger
Heat stroke is very likely.
125 degrees or more
Definitions of risk levels come from NOAA.
Hundreds of people die each year from oppressive heat in the United States. In hot weather, the National Weather Service recommends people drink fluids, stay in cooler rooms, stay out of direct sunlight, and watch relatives and neighbors, especially the elderly and those living alone.
Over the next week, dangerous heat levels are expected in many parts of the contiguous United States. Forecasts become less reliable as they move further into the future.
Heat index forecast for the next six days
The charts show the highest forecasts each day.
Caution
Feel 80°-90°
extreme caution
90°-103°
Danger
103°-124°
Summer temperatures have become hotter and more extreme in recent decades, and the health effects of extreme heat can be severe.
Methodology
The charts on this page are as of 4:37 a.m. on August 7, 2022, according to data from the National Oceanic and Atmospheric Administration. All data shown is forecast, including maps for the date of publication.
The highest predicted heat index is calculated using all available hourly forecasts for each day published by NOAA. For a few days later, forecasts are only released every three or six hours. This means that higher heat indices are more accurate for newer cards.
Population calculations are based on US Census Bureau census tract population centers. Areas are determined to be at risk of hazardous heat if the population center of the area is expected to be exposed to a heat index of 103 degrees or greater.