Tamil Nadu likely to receive normal N-E monsoon rainfall: TNAU

Tamil Nadu is expected to receive normal rainfall during the North-East Monsoon 2026, with the seasonal total forecast at around 468 mm, marginally above the Long Period Average (LPA) of 464 mm, according to the Tamil Nadu Agricultural University (TNAU).

The forecast, prepared at a 60 per cent probability level using the Southern Oscillation Index (SOI) and Sea Surface Temperature (SST) values of the Pacific and Indian Oceans during July-August, was generated using the Australian Rainman International V4.3 software.

The State received 254 mm during the South-West Monsoon (June-September) against the normal 292 mm, recording a 13 per cent deficit as of September 22. The N-E Monsoon, which contributes nearly half of Tamil Nadu’s annual rainfall, is therefore expected to provide some relief to soil moisture, reservoir storage and groundwater recharge, a press release from the university said.

The district-level forecast points to considerable variation around the State average. Mayiladuthurai is projected to receive 991 mm, 9 per cent above its normal rainfall of 910 mm, while Chengalpattu is forecast at 780 mm, 8 per cent above normal.

Nagapattinam is expected to receive 864 mm, 2 per cent above normal, and Kanyakumari 524 mm, 5 per cent above normal. Chennai, with a normal N-E monsoon rainfall of 751 mm, is forecast to receive 730 mm, a 3 per cent deficit.

Several interior districts are expected to record below-normal rainfall. Kallakurichi and Krishnagiri are forecast to be 9 per cent below normal, while Pudukkottai is also projected at a 9 per cent deficit. Namakkal, Thiruvarur and Tirupatthur are forecast to see deficits of 8 per cent each.

Among the southern districts, Madurai is projected to receive 393 mm, 7 per cent below normal, while Tirunelveli and Thanjavur are expected to record deficits of 6 per cent each. TNAU has advised farmers to make use of weather forecasts and agro-advisories for decisions on sowing, irrigation and fertilizer application.

It has also recommended harvesting and storing excess rainwater in farm ponds for use during subsequent dry periods. Measures such as mulching, random tie-ridging and conservation furrows have been suggested for conserving soil moisture in rain-fed areas.

In rice fields, farmers have been advised to adopt Alternate Wetting and Drying (AWD) wherever feasible to improve water-use efficiency. The university has also advised farmers to maintain adequate drainage facilities and adopt ridge-and-furrow sowing in areas likely to receive excess rainfall.

In black soils, broad-bed furrows have been recommended to minimise waterlogging. While the N-E Monsoon is critical for the State’s agriculture and water resources, the distribution of rainfall across districts, rather than the seasonal aggregate alone, is likely to remain important for farm operations and reservoir management during October-December.