heat index
noun
plural heat indexes or heat indices
: a value that indicates what the ambient temperature feels like to the human body and that is derived from a calculation using air temperature and relative humidity
The most likely chances for a heat advisory are Thursday and Friday, when the heat index could approach at least 100 degrees, according to National Weather Service meteorologists …—
Julie E. Greene
Julie E. GreeneThe heat index is defined as a function of temperature and relative humidity. The combination of the two results in an apparent temperature that gives an idea of what the hot and humid air feels like to the average person.—Neil MacFarquhar
Neil MacFarquharExamples of heat index in a Sentence
Recent Examples on the Web
The study used heat index, rather than just air temperature, to take relative humidity into account, Ailshire noted in the release.
—Khloe Quill, Fox News, 5 Mar. 2025
Wednesday forecast High: 96 Low: 75 Partly cloudy skies with a heat index up to 104 degrees.
—Bianca Moreno-Paz, Austin American-Statesman, 16 Sep. 2024
Based on the weekend's temperatures, this year’s festival had an average high of 93 degrees with heat indexes stretching into triple digits in the blazing sun, hotter than any previous Bonnaroo’s average temperature for more than 10 years.
—Melonee Hurt, Nashville Tennessean, 17 June 2024
Schools with no air conditioning in gyms that are hotter than the outside heat index play PE-style games around desks in cooler classrooms.
—Bill Frist, Forbes, 22 Jan. 2025
In Caribou, Maine, for example, the NWS issued its first-ever excessive heat warning for a heat index near 110°F on June 19.
—Andrew Freedman, Axios, 15 Jan. 2025
An extreme heat belt is also emerging from Texas, bringing heat indexes of 110-115°F to Iowa.
—Linh Ta, Axios, 3 Jan. 2025
An excessive heat watch will be in effect across Indiana Tuesday with the possibility of heat index values of up to 107.
—Katie Wiseman Indianapolis Star, Indianapolis Star, 26 Aug. 2024
According to the weather service, the area can expect heat index values as high as 105.
—Diana Leyva, The Tennessean, 16 Aug. 2024
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Khloe Quill, Fox News, 5 Mar. 2025
Wednesday forecast High: 96 Low: 75 Partly cloudy skies with a heat index up to 104 degrees.
—Bianca Moreno-Paz, Austin American-Statesman, 16 Sep. 2024
Based on the weekend's temperatures, this year’s festival had an average high of 93 degrees with heat indexes stretching into triple digits in the blazing sun, hotter than any previous Bonnaroo’s average temperature for more than 10 years.
—Melonee Hurt, Nashville Tennessean, 17 June 2024
Schools with no air conditioning in gyms that are hotter than the outside heat index play PE-style games around desks in cooler classrooms.
—Bill Frist, Forbes, 22 Jan. 2025
In Caribou, Maine, for example, the NWS issued its first-ever excessive heat warning for a heat index near 110°F on June 19.
—Andrew Freedman, Axios, 15 Jan. 2025
An extreme heat belt is also emerging from Texas, bringing heat indexes of 110-115°F to Iowa.
—Linh Ta, Axios, 3 Jan. 2025
An excessive heat watch will be in effect across Indiana Tuesday with the possibility of heat index values of up to 107.
—Katie Wiseman Indianapolis Star, Indianapolis Star, 26 Aug. 2024
According to the weather service, the area can expect heat index values as high as 105.
—Diana Leyva, The Tennessean, 16 Aug. 2024
Articles Related to heat index
Cite this Entry
“Heat index.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heat%20index. Accessed 15 Mar. 2025.
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