When is the first day of Spring, Summer, Fall, and Winter?
Quick Answer: The first day of Spring is the March equinox (around March 20-21). Summer starts at the June solstice (around June 20-21). Fall begins with the September equinox (around September 22-23). Winter kicks off at the December solstice (around December 21-22).
These dates mark when the sun reaches key points in its yearly path across the sky. Equinoxes happen when day and night are nearly equal in length. Solstices are when the sun hits its highest or lowest point relative to the equator.
Because Earth’s orbit isn’t perfectly regular, these dates can shift slightly each year. Still, they reliably signal the start of each season in the Northern Hemisphere.