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
The 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

Examples of heat index in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Related Articles Heat advisory in effect as heat index temps reach triple digits Cramps? Cindy Krischer Goodman, Sun Sentinel, 19 July 2024 By the time the Americans’ chartered plane left the Abu Dhabi airport Thursday, the temperature was about 102 degrees with a heat index of 114 degrees — on the cooler side for the last week. Joe Vardon, The Athletic, 18 July 2024 Three Dade Correctional Institution prisoners, represented by the Florida Justice Institute, said in the class-action suit that the state facility’s heat index surpasses 100 degrees in the summer. Minnah Arshad, USA TODAY, 1 Nov. 2024 Heat risk: Because heat does not pose the same kind of damage to property, CoreLogic defines heat risk as consecutive days exceeding 95 degrees Fahrenheit or temperatures exceeding the 98th percentile of local temperatures, as well as the frequency of extreme heat index days. Mira Rojanasakul, New York Times, 30 Sep. 2024

Word History

First Known Use

1984, in the meaning defined above

Time Traveler
The first known use of heat index was in 1984

Dictionary Entries Near heat index

Cite this Entry

“Heat index.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/heat%20index. Accessed 22 Dec. 2024.

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!