heat wave

American  

[heet weyv] / ˈhit ˌweɪv /

Or heatwave

noun

Meteorology, Climatology.

1. a period of abnormally hot and usually humid weather; heat event.

   I moved to the coast up north because summer back home has become one long, unbearable heat wave.

2. an air mass of high temperature covering an extended area and moving relatively slowly.

   Another heat wave is expected to form across the South and into the Northeast by week’s end.

---

heat wave British  

noun

1. a continuous spell of abnormally hot weather

2. (not in technical use) an extensive slow-moving air mass at a relatively high temperature

---

Etymology

Origin of heat wave

First recorded in 1875–80

Example Sentences

The ongoing heat wave shattering dozens of temperature records in Southern California is no exception, Swain said.

From Los Angeles Times • Mar. 20, 2026

“This is a pretty unprecedented heat wave because of the duration of it,” Steward said.

From Los Angeles Times • Mar. 18, 2026

The outage comes as Southern California broils under a multiday heat wave that has sent temperatures climbing into the 80s and 90s across the Southland.

From Los Angeles Times • Mar. 18, 2026

Climate scientist Daniel Swain described it as “a full-on summer heat wave in March” in a post on X.

From Los Angeles Times • Mar. 17, 2026

A week ago, right at the beginning of the heat wave, the air conditioner in his mother’s attic office had broken.

From "The Lemonade War" by Jacqueline Davies

Related Words

• dog days