Northeast Monsoon's Precarious Exit From South: Light Rainfall May Continue
Key Takeaways
- Northeast Monsoon ended three weeks late due to unseasonal tropical systems.
- South Peninsula ended the season with a marginal 3% surplus, despite deficits in Kerala and Karnataka.
- A depression over the Southwest Bay of Bengal extended rains into January.
- Another winter rain spell is likely between 23rd and 25th January 2026.
The Northeast Monsoon has formally vacated the South Peninsula with a bizarre delay of three weeks. The winter monsoon’s stipulated stay is till December end, with acceptable marginal variations. However, courtesy of unseasonal tropical systems, the monsoon strangely extended its stay this season. Overall, the season was just normal for the earmarked meteorological sub-divisions of South India. Between 01st Oct and 31st Dec 2025, the seasonal rainfall inexpicably remained deficit over the otherwise rainiest state of Kerala. Even the state of Karnataka also fell short of target. Overall, the South Peninsula, as a region, managed to pull a decent number with a marginal surplus of 3% seasonal rainfall.
An uncommon weather system had come up at the fag end of December and the start of January to extend the rainy season. A depression had formed over the Southwest Bay of Bengal, in the proximity of Sri Lanka, Gulf of Mannar and Palk Straits. The weather system had lingered over the region for an extended duration, delaying cessation of monsoon activity. This was further followed up with some other trailing systems in the equatorial region, continuing rainfall activity. Kerala, Tamil Nadu and South Interior Karnataka have gathered large excess rainfall between 01st and 20th January. Some more rains are likely on the approaching weekend.
The island nation Sri Lanka has an extended stay of Northeast Monsoon from October to January. At times, the active conditions continue even thereafter. Locally, the stream is called ‘Maha Monsoon’ and is the second rainiest season after the Southwest Monsoon. The weather systems, more often the easterly waves, keep forming over the equatorial region and run across the North Indian Ocean in the proximity of the equator. These systems do make some insertions and extend the weather activity northwards to reach extreme southern parts of Tamil Nadu and Kerala.
Cessation of Northeast Monsoon does not absolve the South Peninsula completely of winter rains. One such spell is likely between 23rd and 25th Jan 2026. These spells will keep intruding into the southernmost states, albeit at irregular and infrequent intervals, till such time the Northeast Monsoon vacates Sri Lanka.
