The changing dates trigger biological "clocks" in animals, signaling migration, hibernation, and mating seasons.
If you want to mark the official change in daylight and Earth's orbit, follow the astronomical dates (solstices and equinoxes). If you want a simpler, consistent way to track the weather, follow the meteorological seasons. dates of seasons
This guide breaks down the two main ways we calculate seasonal dates— and Meteorological —and provides a calendar for the current year. The changing dates trigger biological "clocks" in animals,