Ritu means “season” in ancient Indian calendars used in India, Bangladesh, Nepal and Sri Lanka. There are six ritus or seasons. The word is derived from the Vedic Sanskrit word Ṛtú.
Every season, different festivals are celebrated in India.
Vasanta rithu (chaitra, vaishakha) – Spring/ Beginning of Summer – March & April
Grishma rithu – (Jyeshta, Ashada) – Peak Summer/Humid – May and June
Varsha rithu – (Shravana, Bhadrapada) – Monsoon – July and August
Sharath rithu (Ashwayuja, karthika) – Late Monsoon – Late September, October, and mid-November
Hemantha rithu (Margashirsha, Pushya) – Beginning of Winter – Late November and December
Shishira rithu – (Magha, Phaguna) – Peak Winter – January and February