Happy Vernal Equinox 2025. The vernal equinox — is an astronomical phenomenon when the sun, in its visible motion along the ecliptic, crosses the celestial equator. The vernal equinox — is an astronomical phenomenon when the sun, in its visible motion along the ecliptic, crosses the celestial equator.
Depending on the approach, spring in the northern hemisphere starts either on the vernal equinox (march 20, 2025) or on march 1. In 2025, the official first day of spring is thursday, march 20.