Tarapith is busiest on Saturdays, on amavasya (new moon nights), and during Kali Puja in October/November — when Tantric worship intensifies and the cremation grounds draw larger crowds of sadhus. If you want to see the ritual life at its most concentrated, these are the right times; if you want quieter access to the temple, a weekday morning is better.
The weather follows West Bengal's pattern: October to March is the comfortable window, with cool, dry days. April and May are brutal before the monsoon arrives in June. The monsoon itself (June–September) is perfectly manageable and gives the flat landscape a lush, green character.