Arhat muni chaturmas (Chaumasa) is the four-month monsoon period in Jainism when monks and nuns stay in one place and lay followers increase their spiritual practices.

• Why it happens: To avoid harming tiny life forms that proliferate during the rains, and to deepen study, meditation, and vows. Monks/nuns do not travel, and lay devotees often take stricter vows and attend more discourses. This four-month period is often linked with intensified observances like samayik, pratikraman, and study of scriptures. End-to-end practice and exact rules can vary a little between Digambar and Śvetāmbara communities. You can read more here and here .

• Typical timing in the modern Jain calendar: Chaturmas usually runs during the rainy season and shifts a year to year. For 2025, it starts around Ashadha Shukla Ekadashi and ends around Kartik Shukla Ekadashi (roughly early July to early November). The commonly cited dates give a start in early July 2025 and an end in early November 2025. You can read the date details here and here .

• Special notes for Arhat-related context: In Jain tradition, great teachers (including the Tirthankaras) are said to have observed Chaturmas as a model for the sangha. The last Chaturmas of a Tirthankara like Mahavira is noted in tradition as a significant period before moksha. This emphasis on staying in one place and deepening spiritual practice is part of the broader Chaturmas ethos. For context, see general explanations of Chaturmas in Jain practice here and here .

If you want, I can share more about how Digambara and Śvetāmbara communities observe Chaturmas differently, and what specific vows or rituals are common in your tradition.