Chaumasa (or Chaturmas) is the four-month period during the monsoon when Jain monks stay in one place and lay followers observe increased austerities. There isn’t a canonical or universal “kaal” (time rule) about boiled water that applies across all Jain traditions specifically for Chaumasa.

• In general Jain practice, boiling water is not forbidden in Chaumasa; many households and practitioners continue to drink boiled (hot) water as needed for health and comfort.
• There can be small, local/temple-specific customs, and there are differences between Digambar and Shwetambar communities on various fasts and puri rules. If a local guru or temple has a particular rule about boiled water during Chaumasa, that rule would be followed in that community.
• If you are asking in a specific ritual or village context (or for a particular Digambar/Shwetambar lineage), please tell me the exact tradition, and I can describe that group's stance more precisely.

If you’d like, I can point you to a JainKnowledge page that discusses Chaumasa rules in more detail from the perspective of your tradition.