Time and Date. Seasons can be defined in several different ways. The astronomical definition is based on the equinoxes and solstices, and spring begins with the spring equinox or vernal equinox. In the Northern Hemisphere, it is the equinox in March; south of the equator, it’s the September equinox.
When Is the First Day of Spring 2023?
Resource Link: https://www.timeanddate.com/calendar/spring-equinox.html