Tamil Nadu has recorded 51% surplus rainfall in the first 27 days of the northeast monsoon, sharply improving the state’s water position after it ended the southwest monsoon with a 16% deficit. However, five districts continued to record deficient cumulative rainfall as of October 27, keeping district-level monitoring important.
The state received 217mm of rain between October 1 and 27, against the normal 144mm for the period, according to data cited by commissioner of revenue administration and disaster management B Chandra Mohan. Eighteen of the 23 districts that were in the rainfall-deficient category at the close of the southwest monsoon have since moved into normal or excess categories.
No district recorded deficient rainfall during October up to October 27. Coimbatore received 313mm against a normal 137mm during the 27-day period, representing a 128% surplus. Tirunelveli recorded 258mm against 123mm, a surplus of 110%, while Dindigul received 328mm against a normal 166mm, a 97% surplus.
Several western and interior districts, including Erode, Karur, Namakkal and Tiruppur, also recorded substantial gains during the period. Chennai received 289mm, which was 33% above its normal rainfall for the 27-day period.
The improvement is less even when rainfall is assessed across the longer June 1 to October 27 period. Tirunelveli remained in the large-excess category, while Tenkasi, Dindigul, Coimbatore and Perambalur recorded excess rainfall. Chengalpet, Thanjavur, Kancheepuram, Vellore and Tuticorin continued to remain deficient, with departures from normal of 38%, 30%, 24%, 22% and 20%, respectively.
Tuticorin’s deficit has narrowed considerably from the 65% recorded at the end of the southwest monsoon. However, rainfall during October was only close to normal in the district, leaving the earlier shortfall reflected in its cumulative position, Chandra Mohan said.
Officials cautioned that rainfall distribution can vary significantly within a district, especially across reservoir catchments. A reduction in the rainfall deficit does not automatically indicate a corresponding improvement in groundwater levels or reservoir storage. “With November and December still ahead, the season remains in progress,” Chandra Mohan said, adding that continued monitoring would be important in districts where deficits persist and in catchments with uneven rainfall distribution.
