Mar. 20th. – First Day of Spring
Astronomically speaking, the equinox (March 19 or 20 every year) marks spring’s beginning in the Northern Hemisphere. The equinox happens at the same moment worldwide, even if our clock times reflect a different time zone.
The first day of the spring season is the day of the year when the Sun crosses the celestial equator moving northward (on March 20th or 21st). This day is known as the Vernal Equinox.