Autumn begins on Friday
Autumn officially begins just before dawn, at 4:04 a.m. local time on Friday, as the fall equinox occurs in the Northern Hemisphere, where Greece is located. Spring will begin in the Southern Hemisphere at the same time.
At the equinox, night and day last nearly the same amount of time. The days will thereafter shorten and the nights will extend in the Northern Hemisphere, until the winter solstice in December, after which the days will start growing longer again.
Source : Newsroom Σύνδεσμος