. For the Southern Hemisphere, these dates are reversed (e.g., March 20 marks the start of Autumn). Time and Date 1. Astronomical Seasons Astronomical seasons begin at the
The next time someone asks you, "When does winter start?" you can confidently reply: "Astronomically on December 21 or 22, but meteorologically on December 1. Which system would you like to use?" when do the four seasons start and end