Ritu (season)
Ritu means "season" in different ancient Indian calendars used in India, Bangladesh, Nepal and Sri Lanka. There are six ritus or seasons. Seasons are different times of the year and there are 12 months in the year. Every month has its own special season. 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.
Nepalese and Indian calendars
Nepal and India observes six ecological seasons.| 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. | Ugadi, Gudi Padwa, Holi, Rama Navami, Puthandu, Vishu, Rongali Bihu, Baisakhi, 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 Purnima, Ratha 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 Janmashtami, Ganesh Chaturthi, Nuakhai, Onam, Gurujonar Tithi, Mahalaya Amavasya |
| 4 | Sharada शरत् | Autumn | Ashvina 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, Kati Bihu, Deepavali, Dhanatrayodashi, Kartik Purnima |
| 5 | Hemanta हेमन्त | Pre-Winter/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 completely shed 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. Thai Pongal, Sankranti are celebrated during the month of Pausha. |
| 6 | Shishira शिशिर | Winter/Cold 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, Magh Bihu Shigmo |
East Indian calendars
East Indian calendars start their new year on Mesh Sankranti. The season names corresponds to the Sanskrit Vasanta, Grishma, Varsha, Sharada, Hemanta, Shishira order.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:
Assamese Calendar
Seasons in the Assamese Calendar:| Assamese season | Start | End | Assamese months | English |
| Grishmo | Mid-April | Mid-June | Bohag, Jeth | Summer |
| Borkha | Mid-June | Mid-August | Ahaar, Xaaun | Monsoon |
| Xorot | Mid-August | Mid-October | Bhado, Ahin | Early Autumn |
| Hemanta | Mid-October | Mid-December | Kati, Aghun | Late Autumn |
| Heat | Mid-December | Mid-February | Pooh, Magh | Winter |
| Boxonto | Mid-February | Mid-April | Phagun, Sot | Spring |
Bengali Calendar
Seasons in the Bengali Calendar:| Bangla Ritu | Bengali Months | English Equivalent | Gregorian Months |
| গ্রীষ্ম | বৈশাখ-জ্যৈষ্ঠ | Summer | Mid April - Mid June |
| বর্ষা | আষাঢ়-শ্রাবণ | Monsoon | Mid June - Mid August |
| শরৎ | ভাদ্র-আশ্বিন | Autumn | Mid August - Mid October |
| হেমন্ত | কার্তিক-অগ্রহায়ণ | Early Winter | Mid October - Mid December |
| শীত | পৌষ-মাঘ | Winter | Mid December - Mid February |
| বসন্ত | ফাল্গুন-চৈত্র | Spring | Mid February - Mid April |
Maithili Calendar
Seasons in the Maithili Calendar:Odia Calendar
Seasons in the Odia calendar:| Odia Ritu | Season | Odia months | Gregorian |
| ଗ୍ରୀଷ୍ମ Grisma | Summer | Baiśākha–Jyeṣṭha | April–June |
| ବର୍ଷା Barsā | Monsoon | Āṣāṛha–Śrābaṇa | June–August |
| ଶରତ Sarata | Autumn | Bhādraba–Āświna | August–October |
| ହେମନ୍ତ Hemanta | Pre-Winter | Kārttika–Mārgaśira | October–December |
| ଶୀତ Sita | Winter | Pauṣa–Māgha | December–February |
| ବସନ୍ତ Basanta | Spring | Phālguna–Chaitra | February–April |
South Indian calendars
Malayalam Kannada Telugu Calendar
The Malayalam calendar or Kollam Era, a solar and sidereal Hindu calendar used in Kerala, and in Karnataka they follows a pattern of six seasons slightly different from North Indian Calendars.| Ritu | Season | [Malayalam calendar|Malayalam solar months] | Sanskrit solar months | Gregorian months | Seasonal festivals | |
| 1 | Vasantam വസന്തം వసంతం ವಸಂತ ಋತು | Spring | Makaram -Kumbham-Meenam | Makara -Kumbha-Mīna | February & March | Vasantha Panchami, Holi |
| 2 | Grishmam ഗ്രീഷ്മം గ్రీష్మం ಗ್ರೀಷ್ಮಋತು | Summer | Meenam -Medam-Idavam | Mīna -Meṣa-Vṛṣabha | April & May | Vishu |
| 3 | Varsham വർഷം వర్షాకాలం ವರ್ಷ ಋತು | Monsoon or Rain | Idavam -Mithunam-Karkatakam | Vṛṣabha -Mithuna-Karkaṭaka | June & July | Karkataka Vavu |
| 4 | Sarath ശരത്ത് శరదృతువు ಶರದ್ಋತು | Early Autumn | Karkitakam -Chingam-Kanni | Karkaṭaka -Siṃha-Kanyā | August & September | Rakshabandhanam, Krishna Janmashtami, Onam |
| 5 | Hemantham ഹേമന്തം హేమంతం ಹೇಮಂತ ಋತು | Late Autumn | Kanni -Thulam-Vrischikam | Kanyā -Tulā-Vṛścikam | October & November | |
| 6 | Sisiram ശിശിരം శిశిరం ಶಿಶಿರ ಋತು | Winter | Vrischikam -Dhanu-Makaram | Vṛścikam -Dhanu-Makara | December & January |
Tamil calendar
The Tamil Calendar follows a similar pattern of six seasons as described in the Hindu calendar.| Tamil season Names | English Meaning | Gregorian Months | Tamil Months |
| Ilavenil இளவேனிற்காலம் | Tender heat / warmth | April 15 to June 14 | Chittirai and Vaikāsi |
| Muthuvenil முதுவேனிற்காலம் | Matured heat / warmth | June 15 to August 14 | Āni and Ādi |
| Kar கார்காலம் | Dark Clouds | August 15 to October 14 | Āvaṇi and Puraṭṭāsi |
| Kutir கூதிர் காலம் | Cold / Chill | October 15 to December 14 | Aippasi and Kārtikai |
| Munpani முன்பனிக் காலம் | Early Dew / Mist | December 15 to February 14 | Mārgaḻi and Tai |
| Pinpani பின்பனிக் காலம் | Late Dew / Mist | February 15 to April 14 | Māsi 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.
Similar naming conventions are also used in Tamil: For female Ilavenil. For male Kar.