A study by the Kozhikode-based Centre for Water Resources Development and Management (CWRDM) has found north-to-south variations in the geographical distribution of seasonal and annual rainfall across Kerala.
According to the study titled ‘Kerala Water Resources Assessment 2024: Rainfall, Rivers, Groundwater, and Wetlands 2024’, northern Kerala, comprising Kasaragod, Kannur, Wayanad, Kozhikode, and Malappuram districts, receives the majority of its rainfall from the south-west monsoon. It contributes approximately 71% of the total annual rainfall, while the north-east monsoon contributes only about 14%. Central Kerala, including Palakkad, Thrissur, Ernakulam, Idukki, and Kottayam, also receives a dominant share of rainfall from the south-west monsoon, averaging around 61%, with the north-east monsoon accounting for roughly 17%.
In contrast, the southern districts of Thiruvananthapuram, Kollam, Alappuzha, and Pathanamthitta receive slightly lower contributions from the south-west monsoon, around 46%, while the north-east monsoon contributes a higher proportion of approximately 22%, indicating a more balanced seasonal rainfall pattern.
Meanwhile, an analysis of the rainfall patterns in Kerala between 1970 and 2024 showed that June exhibited a pronounced decreasing trend in several districts, including Pathanamthitta, Ernakulam, Kottayam, and Kannur, indicating substantial reductions in early monsoon rainfall. July continues this pattern, with significant decreases in Kollam, Idukki, and Ernakulam. August rainfall is relatively stable across most districts, although slight increases are observed in Malappuram and Thrissur, while September shows a significant increasing trend in several northern districts, such as Malappuram, Wayanad, Kannur, and Kasaragod, reflecting a strengthening of rainfall during the peak monsoon season. In March, slight increases are noted in Alappuzha, Kottayam, Idukki, and Wayanad, suggesting early pre-monsoon rainfall variability.
A seasonal analysis indicates mixed trends during the south-west monsoon, with decreasing rainfall in Kollam, Idukki, and Ernakulam, and slight increases in northern districts such as Kasaragod, Wayanad, and Kannur. During the north-east monsoon, coastal districts, including Malappuram and Kasaragod, exhibit decreasing trends, whereas Kannur shows an increasing trend, highlighting spatial variability.
District-specific observations reveal that southern districts, including Thiruvananthapuram, Kollam, and Alappuzha, generally experience stable or slightly decreasing rainfall during early monsoon months. Central districts such as Kottayam, Pathanamthitta, Idukki, Ernakulam, Thrissur, and Palakkad exhibit mixed trends with some increases during pre-monsoon months and decreases in early south-western monsoon months. Northern districts, including Malappuram, Kozhikode, Kannur, Kasaragod, and Wayanad, mostly show increasing rainfall trends during south-western monsoon and post-monsoon months, suggesting intensified rainfall there.
Published – October 28, 2025 09:24 pm IST
