when is the equinox

The equinox occurs twice a year: around March 20 (the spring or vernal equinox) and around September 22 or 23 (the autumnal equinox). On these days, the Sun is positioned directly above the equator, resulting in nearly equal lengths of day and night worldwide. In 2025, the autumnal equinox will happen on September 22 at 19:19 BST (British Summer Time) or 18:19 UTC (Coordinated Universal Time).