Strong start to the NE-monsoon
Rainfall Across Tamil Nadu 2025: In October 2025, the Tamil Nadu recorded 23.3 cm of rainfall — about 36 % above the long-term normal of 17.1 cm for the month. This indicates a robust onset of the NE-monsoon period. The capital city region followed suit, with the Nungambakkam weather station in Chennai registering 32.4 cm in October, marking the second-highest October total of the decade.
Year-on-year comparison
In October 2024, Tamil Nadu’s overall rainfall was 21.4 cm — already 25 % above the average. The further increase in 2025 thus underscores a continuing above-normal rainfall trend for the early NE-monsoon phase.
Daily rainfall pattern and monsoon behaviour
The NE-monsoon remained active almost daily through most of October. Such persistence of rainfall suggests favourable moisture inflows and frequent convective systems during the month. As the state received nearly half of its NE-monsoon quota within October itself, the early momentum for the season is strong.
Implications for water resources and agriculture
Static GK fact: Tamil Nadu receives about 48 % of its annual rainfall during the NE-monsoon period.
With October performing so strongly, reservoirs and catchments across the state are likely to recharge early. This helps agriculture (especially paddy and pulses) and reduces drought risk for the season ahead. However, high rainfall intensity also raises flood-risk potential in low-lying or poorly drained areas.
Risks and caveats
Even though the numbers for October are encouraging, reliance on early rainfall does not guarantee a full monsoon success. The later phase (November-December) remains critical. Also, active daily rainfall may challenge surface drainage systems and create urban flooding issues, particularly in metro areas like Chennai.
Outlook and take-aways
The state’s early NE-monsoon performance is positive. If this momentum continues, it could mitigate water stress and boost agricultural operations. Monitoring the distribution (both spatial and temporal) of rain remains key: whether the rainfall is evenly spread or concentrated in a few spells will determine its utility.
Static Usthadian Current Affairs Table
Rainfall Across Tamil Nadu 2025:
| Topic | Detail |
| October 2025 rainfall | 23.3 cm in Tamil Nadu (36 % above normal) |
| Normal for October | 17.1 cm |
| Chennai (Nungambakkam) | 32.4 cm — second-highest October total this decade |
| October 2024 rainfall | 21.4 cm (25 % above average) |
| Monsoon phase | NE-monsoon active almost daily in October |
| NE-monsoon quota | Nearly half received during October |
| Annual rainfall split | Tamil Nadu: ~48 % rainfall during NE-monsoon* |
| Key risk | Flooding and drainage stress due to active rainfall |
