In the United States, the answer depends on whether you’re following the astronomical calendar or the meteorological calendar.

Summer is defined as the three warmest months of the year: June, July, and August . By this definition, summer ends on August 31 .

Summer ends on the autumnal equinox , which typically falls on September 22 or 23 . In 2024, summer ends on September 22 . After this date, daylight becomes shorter than darkness in the Northern Hemisphere.