The climate of Pathanamthitta is tropical, with hot and humid summers and mild winters. The district experiences heavy rainfall during the monsoon season, which lasts from June to September. The southwest monsoon brings the majority of the rainfall to the region, and the district receives an average annual rainfall of around 3000 mm.

The summer season in Pathanamthitta starts in March and lasts till May, with temperatures ranging from 28°C to 36°C. The humidity is also high during this period, making it uncomfortable for tourists to travel. The winter season, which starts in December and lasts till February, is the most pleasant season to visit Pathanamthitta. The temperature during this period ranges from 20°C to 32°C, and the humidity is relatively low.

The monsoon season in Pathanamthitta starts in June and lasts till September. During this period, the district receives heavy rainfall, which can sometimes lead to flooding and landslides. Tourists are advised to avoid traveling to Pathanamthitta during the monsoon season.

The best time to visit Pathanamthitta is from October to February when the weather is pleasant and comfortable for tourists. However, tourists should be prepared for occasional rains, even during the winter months, as Pathanamthitta receives rainfall throughout the year.