2025 Equinox Calendar. The first day of spring (march equinox or vernal equinox) is when the sun shines directly on the celestial equator passing from south to north and the length of day. The first day of spring is march 20, 2024, at 5:02 a.m.

The first day of spring is march 20, 2024, at 5:02 a.m. Autumn equinox 2025 (beginning of astronomical autumn) on the day of the autumn (september) equinox, the sun, moving along the ecliptic, crosses the celestial equator,.