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
As temperatures rise, heat index values could approach the upper 90s.
—
Baltimore Sun Staff,
Baltimore Sun,
6 July 2026
In Hallandale Beach on Sunday, temperatures reached 90 degrees, with heat indexes reaching near 100 degrees, according to the National Weather Service, the Miami Herald reported.
—
Brian Brant,
PEOPLE,
6 July 2026
Thursday is expected to be the warmest day, with heat index values expected to reach the lower 100s, particularly in areas along and south of Interstate 70.
—
Robert A. Cronkleton,
Kansas City Star,
6 July 2026
According to the National Weather Service, Monday’s high is expected to reach 95 degrees, with heat index values as high as 105.
—
Evan Moore,
Charlotte Observer,
6 July 2026
Temperatures reached 90 degrees in Hallandale Beach Sunday, with heat indexes reaching near 100 degrees, according to the National Weather Service.
—
David Goodhue,
Miami Herald,
6 July 2026
Despite triple-digit heat indexes, visitors from across the country gathered in Philadelphia today to celebrate the nation's 250th birthday at the birthplace of American independence.
—
Kyla Guilfoil,
NBC news,
5 July 2026
With heat indices expected to climb into the triple digits, Freedom 250 organizers modified the schedule to reduce attendees' exposure during the hottest part of the day.
—
Mike Stunson,
USA Today,
4 July 2026
The high temperature is expected to reach 96 degrees, with heat index values as high as 102.
—
Eric Stirgus,
AJC.com,
4 July 2026
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Baltimore Sun Staff,
Baltimore Sun,
6 July 2026
In Hallandale Beach on Sunday, temperatures reached 90 degrees, with heat indexes reaching near 100 degrees, according to the National Weather Service, the Miami Herald reported.
—
Brian Brant,
PEOPLE,
6 July 2026
Thursday is expected to be the warmest day, with heat index values expected to reach the lower 100s, particularly in areas along and south of Interstate 70.
—
Robert A. Cronkleton,
Kansas City Star,
6 July 2026
According to the National Weather Service, Monday’s high is expected to reach 95 degrees, with heat index values as high as 105.
—
Evan Moore,
Charlotte Observer,
6 July 2026
Temperatures reached 90 degrees in Hallandale Beach Sunday, with heat indexes reaching near 100 degrees, according to the National Weather Service.
—
David Goodhue,
Miami Herald,
6 July 2026
Despite triple-digit heat indexes, visitors from across the country gathered in Philadelphia today to celebrate the nation's 250th birthday at the birthplace of American independence.
—
Kyla Guilfoil,
NBC news,
5 July 2026
With heat indices expected to climb into the triple digits, Freedom 250 organizers modified the schedule to reduce attendees' exposure during the hottest part of the day.
—
Mike Stunson,
USA Today,
4 July 2026
The high temperature is expected to reach 96 degrees, with heat index values as high as 102.
—
Eric Stirgus,
AJC.com,
4 July 2026
Cite this Entry
“Heat index.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heat%20index. Accessed 7 Jul. 2026.
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