The first day of spring is called the vernal equinox or spring equinox. It is the astronomical start of spring in the Northern Hemisphere, when day and night are nearly equal in length.

Quick Scoop

  • Common name: Spring equinox.
  • Formal name: Vernal equinox.
  • Also called: First point of Aries in some astronomical references.

Why it matters

The vernal equinox marks the seasonal turning point into longer days and warmer weather in the Northern Hemisphere. In the Southern Hemisphere, the same event marks the start of autumn instead.

Simple answer

If you want the shortest version: the first day of spring is the vernal equinox.