Kalutara's climate is warm and humid year-round, with temperatures ranging from the mid-20s to low 30s Celsius. The dry season runs from January to April, with temperatures gradually rising throughout this period, peaking in March and April. From May to August, a brief respite brings slightly cooler temperatures, but still within the mid-twenties. The monsoon season begins in September, bringing consistent temperatures around 28 degrees Celsius until November. December marks a slight return to warmer temperatures before the cycle repeats itself, with February often being the hottest month overall.