when is equinox

The equinox occurs twice a year, around March 20 and September 22-23, when the Sun appears directly above the Earth's equator, resulting in nearly equal day and night lengths globally. In 2025, the March equinox will be on March 20 at 09:01 UTC, and the September equinox will be on September 22 at 18:19 UTC (about 19:19 BST). These moments mark the start of spring and autumn in the Northern Hemisphere, respectively, and the opposite seasons in the Southern Hemisphere.