---
type: Concept
bundle: jyotisha-kala
bundle_version: 0.12.0
id: ritu
title: Ṛtu
iast: Ṛtu
devanagari: ऋतु
description: 'The six seasons of the ritual year, vasanta, grīṣma, varṣā, śarad, hemanta, śiśira, two solar months each, meshed with the ayana structure; NOT a four-season template, NOT weather commentary, NOT literary ornament only.'
darshana:
- Jyotiṣa
text_source: Vedāṅga Jyotiṣa; Sūrya Siddhānta 14
tags:
- ritu
- seasons
- calendrics
- jyotisha
- kala
not:
- term: 'a four-season template'
  why: 'India’s year has six named seasons; the monsoon (varṣā) refuses to fold into “summer.” Mapping ṛtu onto the European four misplaces two seasons and the rites and regimens keyed to them.'
  instead: 'Render ṛtu as one of the six seasons, name it, and keep the Sanskrit term.'
- term: 'weather commentary'
  why: 'The ṛtus are calendrical divisions, two solar months each, meshed with the ayanas: structural positions in the year, not descriptions of the sky today.'
- term: 'literary ornament only'
  why: 'Kāvya loves the seasons, but the sixfold wheel is load-bearing: Vedic ritual sequences, the almanac, and Āyurvedic seasonal regimen (ṛtucaryā, treated medically in ayurveda-consciousness v0.11) all run on it.'
related:
- /concepts/ayana.md
- /concepts/masa.md
- /concepts/samvatsara.md
timestamp: '2026-07-09'
okf_version: '0.2'
license: CC BY-SA 4.0
---

# Ṛtu -- ऋतु

**Not:** a four-season template, weather commentary, literary ornament only

## What It Actually Means

The Indian year has six ṛtus: vasanta (spring), grīṣma (summer), varṣā (monsoon), śarad (autumn), hemanta (early winter), śiśira (late winter), two solar months each. The sixfold division is Vedic, structures the ritual year, and resists the four-season template on principle: the monsoon is not a variant of summer but a season with its own name, rites, and regimen. Three ṛtus fill each ayana, and the māsa scheme meshes beneath them. Āyurveda’s seasonal regimen runs on the same wheel and is treated medically in ayurveda-consciousness v0.11; here the ṛtu is the calendar structure itself.

## Audience Metaphor

Six spokes on the year’s wheel, not four: the monsoon gets its own spoke, as anyone under it will confirm. Two months to a spoke, three spokes to each half-year breath of the Sun, and both the ritual calendar and the physician’s regimen read which spoke is up.

## Citations

1. Vedāṅga Jyotiṣa on the yuga’s seasonal structure -- see [references/lagadha-vedanga-jyotisha.md](../references/lagadha-vedanga-jyotisha.md)
2. Sūrya Siddhānta 14 on seasons within the solar divisions -- see [references/surya-siddhanta.md](../references/surya-siddhanta.md)
