Astronomical Seasons take place on the Equinoxes and Solstices, which means the change from one season to the next does not take place on the 1st of the month as it does with Meteorological Seasons.
Spring (Equinox) March 19-21* – There’s an equal amount of daylight and night.
Summer (Solstice) June 20-22* – This is the day with the longest amount of daylight.
Fall (Equinox) September 21-24* – There’s an equal amount of daylight and night.
Winter (Solstice) December 20-23* – This is the day with the shortest amount of daylight.
*Applies to Northern Hemisphere.