Tamil Nadu is expected to receive normal northeast monsoon rainfall (October to December) of about 468 mm, a little more than the long-time average of 464 mm, the forecast by Tamil Nadu Agricultural University (TNAU), Coimbatore, states.

The university has prepared the forecast at 60% probability level using the Southern Oscillation Index (SOI) and Sea Surface Temperature (SST), utilising as inputs, the values of Pacific and Indian Oceans during July -August calibrated with Australian Rainman International V.4.3 Software.

The State recorded 254 mm during the southwest monsoon (June–September) 2026 against the normal 292 mm, reflecting a 13% deficit as September 22.

The northeast monsoon, the forecast states, is expected to provide partial relief, improving soil moisture, reservoir storage and groundwater recharge.

Prevailing El Niño conditions may influence monsoon circulation, resulting in variable rainfall distribution. Coastal districts may experience intense wet spells associated with cyclonic systems, while interior districts may see more dry spells, especially in December, a TNAU press release said.

The university advised farmers to utilise weather forecasts and agro advisories from for timely decisions on sowing, irrigation and fertilizer application.

Vigilant monitoring of heavy rainfall and cyclone alerts is essential. During wet spells, farmers may harvest and store excess rainwater in farm pond for supplemental irrigation during dry spells. Mulching, random tie ridging and conservation furrows are recommended for soil moisture conservation in rainfed areas. In rice fields, Alternate Wetting and Drying may be adopted wherever feasible to enhance water use efficiency, the press release said.