Autumn is called 'Sharad Ritu' when the hot weather recedes gradually in most parts of India. The two Hindu months of Ashwin and Kartik fall during this season.
It is festival time in India with the most important Hindu festivals falling during this time - Navaratri, Vijayadashami, and Sharad Purnima, to name a few, acording to Hindu Calendar.
The mid-point of Sharad Ritu is marked by the Autumnal Equinox. Equinoxes occur twice a year, in spring and autumn when the tilt of the Earth's axis is inclined neither away from nor towards the Sun. The dates for Autumnal equinox are September 22 or 23 – a time when days and nights have equal number of hours.
Autumnal Equinox is autumn in the northern hemisphere and spring in the southern hemisphere and vice versa. According to Vedic Astrology, Vernal Equinox is called Sharad Vishuva or Sharad Sampat.