Tamil Nadu delta districts brace for heavy rain as Bay low-pressure builds
Synopsis
A low-pressure system over the southwest Bay of Bengal is intensifying fast, putting Tamil Nadu's delta districts — Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, and Pudukkottai — on heavy rain alert for Thursday and Friday. With the southwest monsoon also poised to reach the Andaman Islands by week's end, the state's rainy season is effectively knocking at the door.
Key Takeaways
The RMC has forecast heavy rainfall in Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai , and Pudukkottai on Thursday and Friday .
A low-pressure area over the southwest Bay of Bengal is expected to intensify within the next 48 hours .
Moderate rain is likely across coastal Tamil Nadu and Western Ghats districts on Wednesday .
Chennai is expected to receive moderate rainfall on Wednesday, with high humidity persisting.
The IMD has indicated the southwest monsoon may reach the Andaman and Nicobar Islands by the end of this week.
Authorities are monitoring low-lying and coastal areas for potential waterlogging and flooding risks.
The Regional Meteorological Centre (RMC) has forecast heavy rainfall across several delta districts of Tamil Nadu over the next two days, as a low-pressure area over the southwest Bay of Bengal is expected to intensify further within 48 hours. Coastal and inland regions of the state are on alert as the developing weather system drives enhanced moisture inflow toward the Tamil Nadu coast.
Districts Under Alert
The RMC has specifically warned of heavy rain in the delta districts of Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, and Pudukkottai on Thursday and Friday. Moderate rainfall is also likely across parts of coastal Tamil Nadu and districts along the Western Ghats on Wednesday, under the influence of the developing weather system.
Low-Pressure System and Its Impact
Meteorologists stated that the low-pressure system over the southwest Bay of Bengal remained active and could strengthen further, leading to intensified rainfall activity across the state. The system is also expected to increase wind activity over parts of the sea, prompting officials to keep a close watch on fishing operations and coastal weather conditions. Authorities are closely monitoring low-lying and coastal areas that are particularly vulnerable to waterlogging and flooding during intense rain spells.
What Chennai Can Expect
In Chennai, the weather department has predicted moderate rainfall in parts of the city on Wednesday. Cloudy skies and intermittent showers are expected to provide some relief from the prevailing summer heat, though humidity levels are likely to remain high.
Monsoon Onset on the Horizon
Separately, the India Meteorological Department (IMD) has indicated that the southwest monsoon may begin advancing over parts of the south Bay of Bengal, the Andaman Sea, and the Andaman and Nicobar Islands by the end of this week. The monsoon's advancement is being closely tracked as it signals the start of the annual rainy season across the region. Officials said district-specific alerts would be issued as the low-pressure system's movement and intensity become clearer in the coming days.
Point of View
Nagapattinam, and Mayiladuthurai sit on the Cauvery delta and have historically borne the brunt of Bay of Bengal weather systems. What deserves attention is the convergence of two signals: an intensifying low-pressure area and an imminent monsoon onset over the Andaman Sea. If the low-pressure system tracks northwest as expected, delta districts could see rainfall well above seasonal norms before the official monsoon even arrives. Preparedness in coastal low-lying areas — not just weather advisories — will determine how much of this becomes a crisis.
NationPress
27 Jun 2026
Frequently Asked Questions
Which Tamil Nadu districts are under heavy rain alert?
The RMC has warned of heavy rain in the delta districts of Thanjavur, Tiruvarur, Nagapattinam, Mayiladuthurai, and Pudukkottai on Thursday and Friday. These districts are particularly vulnerable due to their low-lying coastal geography.
What is causing the heavy rainfall forecast for Tamil Nadu?
A low-pressure area over the southwest Bay of Bengal is expected to intensify within 48 hours, driving increased moisture inflow toward the Tamil Nadu coast. The developing system is also expected to heighten wind activity over the sea.
Will Chennai be affected by the rain?
Yes, the weather department has predicted moderate rainfall in parts of Chennai on Wednesday. Residents can expect cloudy skies and intermittent showers, though humidity levels will remain high.
When is the southwest monsoon expected to arrive?
The IMD has indicated the southwest monsoon may begin advancing over the south Bay of Bengal, the Andaman Sea, and the Andaman and Nicobar Islands by the end of this week, marking the start of the annual rainy season.
What precautions are authorities taking?
Officials are closely monitoring low-lying and coastal areas vulnerable to waterlogging and flooding. Fishing operations are also under watch due to increased wind activity over the sea, and district-specific alerts will be issued as the system develops.
