Keralam adjusts to Northeast Monsoon after 28% deficit of Southwest Monsoon

A significant shift in wind direction from westerly to easterly has already occurred and the India Meteorological Department (IMD) is expected to announce the onset within the next 24 hours, with the prescribed criteria almost met. (file image) | Photo credit: THULASI KAKKAT

After a deficient southwest monsoon season which was 28% in Kerala, the stage is set for the onset of northeast monsoon over the state and southern peninsula with mixed rainfall prospects. A significant shift in wind direction from westerly to easterly has already occurred and the India Meteorological Department (IMD) is expected to announce the onset within the next 24 hours, with the prescribed criteria almost met.

Speaking to The Hindu, Neetha K. Gopal, Director, IMD, Thiruvananthapuram, said the withdrawal criteria for the southwest monsoon is expected to be met by October 15, paving the way for the simultaneous onset of the northeast monsoon. Persistent surface vents were formed which triggered rainfall over the southernmost parts of Tamil Nadu. By Thursday (October 15, 2026), rain is expected to spread to other parts of Tamil Nadu, including the entire coast as well as adjoining areas of Andhra Pradesh, marking the beginning of two-and-a-half months of northeast monsoon over south India, including Kerala, she said.

The onset is expected to bring a decent initial spell of rainfall to Kerala, aided by circulation over north Keralam and neighboring Karnataka and also Bay of Bengal systems.

Rain warning

The IMD on Thursday issued an orange alert for Pathanamthitta, Kottayam, Idukki and Ernakulam, warning of intense heavy rainfall, and a yellow alert for the remaining districts, except Kannur and Kasaragod, due to isolated heavy rains. Rain activity is expected to be more pronounced during the afternoon and night, with light to moderate showers likely for the rest of the day.

Although decent rain is expected in October, cyclone formation over the Bay of Bengal in late October and November remains uncertain. Climatologically, more weather systems develop over the bay in November, increasing rainfall activity mainly in south and central Kerala.

However, a strengthening El Niño over the Pacific is also expected to affect rainfall in the Indian subcontinent. Rising atmospheric temperatures and sea levels are expected to increase the atmosphere’s ability to hold moisture.

Additional heat

The additional heat may contribute to heavy rainfall and stronger cyclonic systems, interspersed with extended dry spells, climate scientists said. However, energy transfer through the atmosphere-ocean system is not instantaneous, and the effects could sometimes extend into the following monsoon season. Theoretically, an increase in cyclonic activity could be seen this year or next year.

At the same time, El Niño can suppress the vertical movement of air, disturb the exit of warm air full of moisture and thus suppress precipitation. The end result could be a pattern of short, intense wet periods triggered by Bay of Bengal systems, followed by extended dry spells, the researchers said.

Keralam experienced a normal northeast monsoon in 66 out of 125 years from 1901 to 2025. The season was deficient in only 29 years and excess in 30 years, meaning that rainfall was normal or above normal in 96 years. The highest northeast monsoon rainfall was recorded in 2021 when Keralam received 1,026.3 mm against the normal 478.1 mm. The lowest was recorded in 2016 when the state received only 185 mm and a strong El Niño also marked 2016.

Published – 14 Oct 2026 14:56 IST