Chennai, Nov 16, 2025: The Indian Meteorological Department (IMD) has issued warnings of heavy rainfall in parts of Tamil Nadu, including the city of Chennai, as a low-pressure system develops over the southwest Bay of Bengal. Residents and authorities have been advised to prepare for localized flooding and disruptions, particularly in low-lying areas prone to waterlogging.

According to the latest forecast, light to moderate rainfall is expected at isolated locations across Chennai and several other districts in Tamil Nadu on Sunday, with heavier showers likely in specific regions. The rainfall activity has been attributed to the formation of a low-pressure area over the southwest Bay of Bengal, near the coast of Sri Lanka, which has created conditions conducive to widespread precipitation across the state.

IMD Alerts and Forecasts

The IMD has issued an orange alert for Pudukkottai, Thiruvarur, and Mayiladuthurai districts, indicating that heavy rainfall is likely in these areas today. In addition, a yellow alert has been sounded for Thoothukudi, Madurai, Nilgiris, Sivagangai, and several other districts, suggesting the likelihood of moderate rainfall with possible disruptions. Chennai and its surrounding districts—Villupuram, Chengalpattu, Cuddalore, Mayiladuthurai, Nagapattinam, and Tiruvarur—as well as the union territories of Puducherry and Karaikal, are also expected to experience heavy to very heavy rainfall at isolated places.

For Monday, November 17, the IMD forecast indicates that heavy to very heavy rainfall is likely over a few districts including Chengalpattu, Kancheepuram, Villupuram, Puducherry, Thoothukudi, and Kanyakumari. Authorities have been urged to remain vigilant and ensure adequate measures are in place to handle waterlogging and potential flooding.

Impact of the Low-Pressure System

The low-pressure area over the southwest Bay of Bengal is influenced by upper air cyclonic circulation, creating strong winds and instability in the atmosphere. Wind speeds are expected to reach 35 kmph to 45 kmph along and off the Tamil Nadu coast, leading to rough sea conditions. Fishermen and others involved in maritime activities have been advised not to venture into these areas until conditions improve.

Heavy rainfall, combined with strong winds, could disrupt daily life in coastal and low-lying areas, affecting transportation, power supply, and water drainage systems. Authorities have been asked to monitor water levels in rivers, canals, and urban drainage networks, particularly in Chennai, where last month’s widespread rains had already caused significant waterlogging and traffic disruptions.

Preparations and Response

Deputy Chief Minister Udhayanidhi Stalin recently inspected ongoing infrastructure projects and renovation works aimed at improving Chennai’s waterways and drainage systems. These measures are part of the state government’s broader efforts to mitigate the impact of heavy rains, particularly in flood-prone areas. The inspection was intended to ensure that construction and maintenance work along canals, stormwater drains, and rivers is progressing efficiently to prevent urban flooding during the current monsoon spell.

State disaster response authorities, local municipal bodies, and traffic police have been alerted to coordinate responses in case of emergencies. Citizens have been advised to avoid non-essential travel during periods of heavy rainfall and to remain cautious while commuting. Residents in areas with poor drainage infrastructure have also been urged to take necessary precautions, including avoiding low-lying streets and ensuring that essential supplies such as food, water, and medicines are available at home.

Past Rainfall Patterns and Context

Tamil Nadu, particularly the Chennai metropolitan area, has been experiencing significant rainfall over the past several weeks. Last month, widespread rain led to waterlogging across several parts of the city and disruptions in traffic and public transportation. The current weather system is expected to add to the cumulative rainfall, raising concerns about potential flooding, especially in vulnerable areas.

Chennai’s drainage infrastructure has historically struggled to cope with heavy rainfall, particularly during short but intense spells of precipitation. The city’s low-lying areas, such as parts of South and North Chennai, are especially prone to waterlogging. Authorities have emphasized the importance of preemptive measures to ensure that stormwater drains are cleared and that urban flood mitigation systems are operational.

Warnings for Coastal Areas and Fishermen

The IMD has specifically warned that squally weather is likely along the coast, and strong winds may make maritime activities hazardous. Fishermen have been advised to remain ashore and avoid venturing into the sea for at least the next 24 to 48 hours. Small boats and fishing vessels are particularly vulnerable to the combination of heavy rain and strong winds, which could lead to accidents or capsizing.

In addition to the coastal warnings, local authorities have been directed to remain on high alert for landslides and flooding in hilly regions and other vulnerable locations. The combination of heavy rainfall, strong winds, and poor drainage can result in sudden water accumulation, posing risks to life and property.

Public Advisory and Precautions

Citizens are urged to follow advisories from the IMD and local authorities. Key recommendations include:

• Avoid traveling during periods of heavy rain, especially in low-lying or waterlogged areas.
• Ensure that essential supplies are stocked at home.
• Stay updated on weather warnings and alerts via official channels, including the IMD website and local news.
• Exercise caution near rivers, canals, and coastal areas, particularly where water levels are rising.
• Follow safety instructions issued by municipal authorities and disaster management teams.

Local civic bodies have been instructed to keep pumps, flood-control measures, and emergency response teams on standby to respond quickly to any incidents. Public transportation authorities have also been asked to monitor roads, flyovers, and underpasses to prevent accidents due to waterlogging.

Conclusion

The heavy rainfall forecast in Tamil Nadu, driven by the developing low-pressure area in the southwest Bay of Bengal, poses a significant risk to daily life and infrastructure. With orange and yellow alerts in place, authorities and citizens alike have been urged to take precautions to mitigate the impact. The combination of heavy rainfall, strong winds, and potential waterlogging emphasizes the need for vigilance, preparedness, and adherence to safety advisories issued by the Indian Meteorological Department and state authorities.

Residents of Chennai and surrounding districts are particularly advised to remain alert over the coming days, as the rainfall is likely to continue and could impact commuting, daily activities, and urban infrastructure. With proper preparation and timely action, the potential adverse effects of the weather system can be managed effectively, minimizing risks to life and property.