Here on the left coast, the autumnal equinox occurs today at roughly 1 p.m. At that time the sun will shine directly down upon the equator and the daily length of sunlight and dark will be as close to equal as they ever get.
Today also marks the "official" end of Summer and beginning of Autumn, a season which will end on the 21st of December. I put official in quotes inasmuch as we've already had snowfall at home in the Wyoming Rockies.
For awhile it snows at night and melts during the day, then it gets colder and snow begins to accumulate. This, of course, is why we arrange to be elsewhere during the Rockies' long annual cold spell. We have the CA native's view of snow, it's fun to visit but you don't want to live there.
Upon retirement, the DrsC decided to spend as much of the year as possible in conditions of late Springtime - the "Goldilocks" season of not too hot, not too cold. It's a lot of work but worth it. We have successfully done this for the past 13 years, and hope to continue for many more.