Study flags steady drop in Kerala’s southwest, northeast monsoon rainfall

Kerala experiences a significant decline in monsoon rainfall, raising concerns over climate change impacts and water resource management.

Kerala has reason to worry about increasingly erratic monsoon behaviour, as its average seasonal rainfall during both the southwest and northeast monsoons has shown a steady decline over the past 125 years (1901-2025), according to a report by the Institute for Climate Change Studies (ICCS).

ICCS scientists said that Kerala’s average rainfall during the southwest (June–September) and northeast (October–December) monsoons, the State’s primary sources of rainfall, decreased by 12.5% and 6.1%, respectively, of the long-period average (LPA, 1971–2020) per 100 years.

While the LPA for southwest monsoon rainfall in Kerala is 1,919.3 mm, the LPA for northeast is 478.1 mm.

The information, released as part of the ‘Statement on Climate for the State of Kerala: 2025’, said the average southwest monsoon rainfall during 1901–2025 showed a decreasing trend in all districts except Idukki.

Nine districts, Kottayam, Alappuzha, Kollam, Pathanamthitta, Kannur, Wayanad, Kozhikode, Malappuram, and Palakkad, reported a “significantly decreasing” trend, while Ernakulam, Thrissur, and Kasaragod showed a “decreasing” pattern. In Idukki, an “insignificant increasing” trend was observed.

In the case of the northeast monsoon, decreasing seasonal rainfall was recorded in all districts except Kasaragod, with “significantly decreasing” trends observed in Wayanad, Palakkad, and Kottayam. Kasaragod showed an “insignificant increasing” trend.