Tamil Nadu records 51% rainfall surplus in October; Nilgiris cumulative deficit narrows to 13%

Deck: TNDRRA figures cited by two newspapers show 217.2 mm against a 144.2 mm normal from 1–27 October. The Nilgiris’ cumulative rainfall deficit eased from 32% to 13% by 27 October.

Tamil Nadu received an average of 217.2 mm of rainfall between 1 and 27 October, against the period’s normal of 144.2 mm — a surplus of 51%, according to figures from the Commissionerate of Revenue Administration and Disaster Management (TNDRRA) cited by The New Indian Express and The Times of India.

The rainfall has substantially improved the state’s cumulative position after it ended the southwest monsoon with a 16% deficit. By 27 October, the state’s cumulative rainfall since 1 June was less than 1% below normal. Eighteen of the 23 districts that were in deficit at the end of September had moved into the normal or excess categories; five districts continued to show cumulative deficits.

The Nilgiris’ cumulative rainfall departure improved from a 32% deficit to a 13% deficit by 27 October. This is a change in the cumulative seasonal position, not a claim that every part of the district received the same amount of rain.

Revenue Administration Commissioner B. Chandra Mohan cautioned that rainfall can vary considerably within a district, including across reservoir catchments. A smaller rainfall deficit does not by itself prove that groundwater levels or stored water have recovered. The northeast monsoon season is still in progress.

Key figures

• Period measured: 1–27 October 2026
• Tamil Nadu average: 217.2 mm
• Normal for the period: 144.2 mm
• October surplus: 51%
• Nilgiris cumulative departure: improved from −32% to −13%
• State cumulative position since 1 June: less than 1% below normal as of 27 October

Image disclosure: Contextual image of misty tea-growing hills; it is not a photograph of a specific rainfall event or a measured rain gauge. Photo: ABHIRAM PH / Unsplash.