First Day Of Spring Summer Fall Winter 2024 Season. The season change dates are based on the spring and fall equinoxes as well as the summer and winter solstices. Fall starts at the moment when the sun is directly over the equator, going from north to south:
By that calendar, spring starts on march 1, summer on june 1, fall on sept. In one year, earth revolves completely around the sun while rotating on an invisible axis, like a tilted, spinning top.