October ends with excess rainfall over T.N. for second consecutive year; IMD indicates below normal rains in November

The month of October ended with heavy rains for the second consecutive year in Tamil Nadu amid the active northeast monsoon. After a few days of dry weather, rainfall activity is expected to increase marginally in the state from November 5 onwards.

The state recorded a total rainfall of 23.3 cm in October, which was 36% above its normal share (17.1 cm). While most districts ended the month with normal to above normal rainfall, a few districts including Ranipet, Tirunelveli and Vellore recorded major excess rainfall following heavy showers.

In October 2024, Tamil Nadu had received 21.4 cm of rainfall, which was 25% above the monthly average. This October, Chennai region also recorded excess rainfall for the second year in a row.

Chennai’s Nungambakkam weather station recorded the second highest October rainfall of the decade at 32.4 cm. Last year holds the record for the highest October rainfall in Nungambakkam in the last decade.

B. Amudha, Chairman (Additional Officer), RMC, said that the Northeast monsoon has performed well in the last five years, bringing either normal or excessive rainfall to the State. “This October, the state received rainfall almost every day except the last few days. The active monsoon phase contributed to excessive rainfall,” he said.

Noting that the first few days of November will bring only dry weather over TN, she said models indicated an increase in rainfall from November 5, with more clarity expected in one or two days.

Meanwhile, the India Meteorological Department (IMD) has predicted that November rainfall in the state is likely to be below normal rainfall. In its monthly rainfall and temperature outlook, the ministry predicted that rainfall will be below normal in most regions. Except for a few areas along the Western Ghats, the state is likely to experience above-normal temperatures.

In a long-range forecast based on the South Indian Ocean Convergence Zone model, a team of former meteorologists at IMD, including Onkari Prasad, showed the possibility of normal rainfall in November. Areas like Kallakurichi, Erode and Tiruvarur may experience heavy rainfall.

Former Deputy Director General of Meteorology YEA Raj said that southwest monsoon rains in the first two weeks of October and early onset of northeast monsoon helped the State watch excessive rainfall. Weather system over Arabian Sea lasting more than 10 days also increased monsoon rainfall in TN

He added that while the state has already recorded almost half of the Northeast monsoon quota in October, the season, known for its alternating wet and long dry spells, could even out the overall rainfall distribution.