An IMD study found that southern India has become wetter over seven decades

People walk on the coast amid heavy rains and strong gales caused by Cyclone Murasu in Ongola, Prakasam, November 3, 2026. | Photo credit: ANI

South India has become wetter over the past seven decades as the area classified as a hot semiarid climate nearly halved from about 30% to 16% of the peninsula between 1951-1980 and 1991-2020, according to a study by scientists from the India Meteorological Department (IMD) and the Indian Institute of Tropical Meteorologists (II.TM.

A study published in MAUSAM, a peer-reviewed IMD journal, found that much of the peninsula’s hot, semi-arid regions have shifted to a tropical savanna climate zone, with more rainfall and extended dry periods.

This zone now covers nearly three-quarters of peninsular India, compared with about three-fifths in the 1950s. The study, titled “Identifying Climate Zonal Shifts of India’s Meteorological Subdivisions: Insights from Historical Records,” uses the Köppen-Geiger climate classification system to assess changes across India’s meteorological subdivisions.

Northwest India is drier and warmer

The researchers mapped India’s climate zones over consecutive 30-year periods using IMD precipitation and temperature observations from 1951 to 2020. They found that most of the shift in southern India occurred during the two most recent periods, 1981-2010 and 1991-2020, primarily due to an increase in precipitation.

The trend in southern India contrasts with that in northwest India, where a hot semi-arid zone has spread from west to eastern Uttar Pradesh amid declining rainfall. Meanwhile, day and night temperatures have risen across the country.

Impact on the farm

The researchers said changes in climate zones could have implications for agriculture, particularly in determining suitable crops and sowing times. They emphasized the need to monitor these shifts and incorporate them into long-term agricultural planning.

This year, the IMD Regional Meteorological Center in Chennai has declared the onset of the Northeast Monsoon on October 15, 2026, five days ahead of its normal date. The IMD has predicted a normal northeast monsoon for Tamil Nadu against the seasonal average of 44 cm. While the Cauvery delta and southern regions are likely to see normal to above normal rainfall, the northern interior regions are expected to experience below normal rainfall.

Tamil Nadu ended the June-September southwest monsoon with a 20% rainfall deficit. The country as a whole saw a 12.6% deficit during the season as El Niño conditions contributed to the weakening of the southwest monsoon.

Ananya Karmakar of IMD Pune, lead author of the study, said the long-term increase in rainfall in the peninsula is an important factor to consider in water and agriculture planning in Tamil Nadu, given the state’s dependence on the northeast monsoon.

Mrutyunjay Mohapatra, director general of meteorology at IMD and co-author of the study, said the ministry’s seasonal forecasts and recommendations for farmers take into account both long-term climate trends and seasonal fluctuations.

Published – 03 Nov 2026 23:17 IST