Equinox stands for equal day and night.
Every year, we get two equinoxes – the Vernal equinox in March and the Autumn equinox in September.
The autumn equinox is on September 22/23 each year.
In the Northern hemisphere, this equinox marks the beginning of the autumn season after the rainy/summer season.
In the Southern hemisphere, the September equinox marks the beginning of spring.