- 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.
- 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.
- a continuous spell of abnormally hot weather
- an extensive slow-moving air mass at a relatively high temperature
