Ritu (Indian season)
Ritu defines "season" in different ancient Indian calendars used in countries, India, Bangladesh, Nepal and Sri Lanka, and there are six ritus or seasons. The word is derived from the Vedic Sanskrit word Ṛtú, a fixed or appointed time, especially the proper time for sacrifice or ritual in Vedic religion; this in turn comes from the word Ṛta, as used in Vedic Sanskrit literally means the "order or course of things". This word is used in nearly all Indian languages.
North, West, and Central Indian calendars, South
Nepal and India observes six ecological seasons. Southern parts of India experiences the seasons on a different schedule than the one depicted here.| No. | Ritu | Season | Hindu lunar months | Gregorian month | Characteristics | Seasonal festivals |
| 1 | Vasanta वसन्त | Spring | Chaitra and Vaishakha | March & April | Temperature around 20-30 degrees Celsius; vernal equinox occurs in the middle of this season. First spring harvest along with harvest festivals. | Vasant panchami, Ugadi, Gudhi Padwa, Holi, Rama Navami, Vishu/Rongali Bihu/Baisakhi/Brahmin New Year, Hanuman Jayanti |
| 2 | Grīṣma ग्रीष्म | Summer/Hot Season | Jyeshtha and Ashadha | ~ May & June | Very hot, temperatures up to 45-50 degrees Celsius; summer solstice occurs. This is one of the two typical Indian/ Hindu Marriage Seasons. | Vat Pournima, Rath Yatra, Guru Purnima |
| 3 | Varṣā वर्षा | Monsoon/Rainy Season | Shravana and Bhadrapada | ~ July & August | Very hot, very humid and heavy monsoon rains; begins with the lunar month AFTER the summer solstice. | Raksha Bandhan, Krishna Janmaashtami, Ganesh Chaturthi, Nuakhai, Onam, Gurujonar Tithi, Mahalaya Amavasya |
| 4 | Sharad शरद् | Autumn | Ashwina or Ashvayuja and Kartika | ~ Late- September, October & mid-November | Mild temperatures; 19-25 degrees Celsius; autumnal equinox occurs in the middle of this season. First autumn harvest occurs along with harvest festivals. Some trees in the Himalayas or upper elevations change colors much like in northern latitudes across the world. | Navaratri, Vijayadashami, Sharad Purnima, Bihu, Deepavali, Dhanatrayodashi, Kartik Purnima |
| 5 | Hemanta हेमन्त | Prewinter/Cool Season | Margashirsha and Pausha | ~ Late November & December | Very pleasant temperatures; generally, 19-25 degrees Celsius; ends with the winter solstice. Some trees in the Himalayas and other hills complete shedding their leaves much like in northern latitudes across the world. | Margashira Mahotsavam. Music Season with a number of Indian Carnatic classical music and dance concerts. |
| 6 | Shishira शिशिर | Winter/Dewy Season | Magha and Phalguna | ~ January & February | Moderately cold, but pleasant during occasional sunshine; temperatures may decrease below 10 degrees Celsius. This season is typical to tropical and subtropical regions because trees actually shed their leaves in this season in tropical areas; starts with the winter solstice. | Shivaratri, Shigmo, Tamil New Year, Sankranthi |
East Indian Calendars
East Indian Hindu calendar.The Bengali Calendar is similar to the Sanskrit calendar above, but differs in start and end times which moves certain dates/days around. The East Indian Calendar has the following seasons or ritus:
| Bengali season | Start | End | Bengali months | ladhaki | English |
| Grishmo | Mid-April | Mid-June | Boishakh, Joishtho | sos ka, སོས་ག | Summer |
| Borsha | Mid-June | Mid-August | Asharh, Srabon | yarka, དབྱར་ཁ | Monsoon |
| Shorot | Mid-August | Mid-October | Bhadro, Ashwin | stonka, སྟོན་ཀ | Early Autumn |
| Hemonto | mid-October | mid-December | Kartik, Ogrohayon | dgun stod, དགུན་སྟོད། | Late Autumn |
| Shit | mid-December | mid-February | Paush, Magh | dgun smid, དགུན་སྨད | Winter |
| Bosonto | mid-February | mid-April | Phalgun, Choitro | shid ka, དཔྱིད་ཀ | Spring |
South Indian Calendars
Malayalam calendar
The Malayalam calendar or Kollam Era, a solar and sidereal Hindu calendar used in Kerala, follows a pattern of six seasons slightly different from North Indian Calendars.| No. | Ritu | Season | Malayalam solar months | Sanskrit solar months | Gregorian months | Seasonal festivals |
| 1 | Vasantam വസന്തം | Spring | Makaram -Kumbham-Meenam | Makara -Kumbha-Mīna | February & March | Vasantha Panchami, Holi |
| 2 | Grishmam ഗ്രീഷ്മം | Summer | Meenam -Medam-Idavam | Mīna -Meṣa-Vṛṣabha | April & May | Vishu |
| 3 | Varsham വർഷം | Monsoon or Rain | Idavam -Mithunam-Karkatakam | Vṛṣabha -Mithuna-Karkaṭaka | June & July | Karkataka Vavu |
| 4 | Sarath ശരത്ത് | Early Autumn | Karkitakam -Chingam-Kanni | Karkaṭaka -Siṃha-Kanyā | August & September | Rakshabandhanam, Krishna Janmashtami, Onam |
| 5 | Hemantham ഹേമന്തം | Late Autumn | Kanni -Thulam-Vrischikam | Kanyā -Tulā-Vṛścikam | October & November | |
| 6 | Sisiram ശിശിരം | Winter | Vrischikam -Dhanu-Makaram | Vṛścikam -Dhanu-Makara | December & January |
Tamil calendar
The Tamil Calendar follows a similar pattern of six seasons as described for north Indian Hindu calendars which in fact need adjustment as taking new year from Grishma like that Bengali calendar....| Tamil season Names | English Meaning | Gregorian Months | Tamil Months |
| Muthuvenil முதுவேனில் | Matured heat / warmth | April 15 to June 14 | Chithirai and Vaikasi |
| Kar கார் | Dark Clouds | June 15 to August 14 | Ani and Adi |
| Kulir குளிர் | Cold / Chill | August 15 to October 14 | Avani and Purattasi |
| Munpani முன்பனி | Early Dew / Mist | October 15 to December 14 | Aipasi and Karthikai |
| Pinpani பின்பனி | Late Dew / Mist | December 15 to February 14 | Margazhi and Thai |
| Ilavenil இளவேனில் | Tender heat / warmth | February 15 to April 14 | Masi and Panguni |
In culture
The seasons are described in literature such as the Sanskrit poem Ṛtusaṃhāra written by the legendary Sanskrit poet Kālidāsa.Names of the ritu are commonly used for persons: typically, Vasant, Sharad, Hemant, Shishir and Varsh are "male" names; "female" names include Vasanti, Sharada, Hemanti, Grishma and Varsha.