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
All of these areas were expected to see heat index values in the triple-digits, according to the NWS.
—Joe Edwards, MSNBC Newsweek, 18 July 2025
Temperatures are expected to rise into the mid-90s, with heat index values near 100 degrees, according to meteorologists.
—Kendrick Calfee, Kansas City Star, 16 July 2025
Temperatures will stick around the upper 90s as heat index values cross into the triple digits again, according to the NWS.
—Brayden Garcia
july 14, Fort Worth Star-Telegram, 14 July 2025
The muggy air will drive up heat index values, making those 90-degree afternoon temperatures feel more like 100 or 102 degrees.
—Mary Wasson, Austin American Statesman, 14 July 2025
Highs around 90 and high humidity, with dewpoints in the 70s, will result in heat index values in the upper 90s to near 100 degrees on Saturday.
—Haadiza Ogwude, The Enquirer, 11 July 2025
Because of cloud cover, highs will be in the upper 80s with heat indexes because of humidity pushing the feels-like temperatures to the mid to upper 90s.
—Richard Tribou, The Orlando Sentinel, 3 July 2025
Peak heat index values are between 99 and 104 degrees.
—Garfield Hylton, The Orlando Sentinel, 7 July 2025
The high Tuesday will be near 92 degrees and heat index values are set to be as high as 102 degrees.
—arkansasonline.com, 7 July 2025
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Joe Edwards, MSNBC Newsweek, 18 July 2025
Temperatures are expected to rise into the mid-90s, with heat index values near 100 degrees, according to meteorologists.
—Kendrick Calfee, Kansas City Star, 16 July 2025
Temperatures will stick around the upper 90s as heat index values cross into the triple digits again, according to the NWS.
—Brayden Garcia
july 14, Fort Worth Star-Telegram, 14 July 2025
The muggy air will drive up heat index values, making those 90-degree afternoon temperatures feel more like 100 or 102 degrees.
—Mary Wasson, Austin American Statesman, 14 July 2025
Highs around 90 and high humidity, with dewpoints in the 70s, will result in heat index values in the upper 90s to near 100 degrees on Saturday.
—Haadiza Ogwude, The Enquirer, 11 July 2025
Because of cloud cover, highs will be in the upper 80s with heat indexes because of humidity pushing the feels-like temperatures to the mid to upper 90s.
—Richard Tribou, The Orlando Sentinel, 3 July 2025
Peak heat index values are between 99 and 104 degrees.
—Garfield Hylton, The Orlando Sentinel, 7 July 2025
The high Tuesday will be near 92 degrees and heat index values are set to be as high as 102 degrees.
—arkansasonline.com, 7 July 2025
Cite this Entry
“Heat index.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heat%20index. Accessed 24 Jul. 2025.
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