There are 6 seasons or 'Ritu' in a year according to the Hindu Calendar. Since Vedic times, the various seasons in the Indian subcontinent was classified into these six categories. While North India mostly conforms to this marked change of seasons, it is less so in South India which is mostly marked by long summers and light winters.
The King of Ritus springtime is called ‘Vasant Ritu’ when it is neither too hot or cold in most parts of India. The two Hindu months of Chaitra and Baisakh fall during this season. It is the time for some important Hindu festivals including a number of new years.
The auspicious occasions of this season are Vasant Panchami, Ugadi, Gudi Padwa, Holi, Rama Navami, Vishu, Bihu, Baisakhi, Puthandu, Hanuman Jayanti, to name a few. Vasant is also known as ‘Rituraj’ or the king of seasons, according to Hindu calendar.
The mid-point of Vasant Ritu is marked by the Vernal 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 equinoxes are March 20 or 21 (Vernal Equinox) and September 22 or 23 (Autumnal Equinox) every year when days and nights have equal number of hours. Vernal Equinox is springtime in the northern hemisphere and autumn in the southern hemisphere and vice versa. According to Vedic Astrology, Vernal Equinox is called Vasant Vishuva or Vasant Sampat.