Weather Update: Heavy Rain Expected Across South India Today (October 16, 2025)
A Crucial Update on the Upper Air Circulation Impacting Tamil Nadu and Neighboring States
Good morning! Today, October 16, 2025, we bring you the latest analysis on the ongoing weather systems affecting South India. Please note that this is a personal weather estimation; for official announcements, always follow the guidance provided by the Indian Meteorological Department (IMD) and government authorities.
The Current Weather System and Support Factors
Currently, an upper air cyclonic circulation (வளிமண்டல மேலடுக்கு சுழற்சி) continues to persist in the Kanyakumari Sea regions, specifically near the equator. This system spans the area between Sri Lanka and the Kanyakumari Sea, with its structure extending up to Karnataka.
Crucially, this circulation is receiving support from the Westerly Wind Burst (WWB), also known as the MJO (Madden-Julian Oscillation). Satellite imagery confirms that the support from the MJO is clearly evident. Specifically, the western and southwestern quadrants of the circulation show significant convection.
This atmospheric configuration has already resulted in heavy rainfall across most parts of Southern Tamil Nadu.
Rainfall Recorded in the Last 24 Hours
The past 24 hours saw significant rainfall, primarily concentrated in the Thoothukudi and Tirunelveli districts.
Notable rainfall measurements include:
- Thoothukudi District: Ammapuram recorded 88.4 mm; Pasuvanthanai recorded 84.8 mm; Kayalpattinam recorded 81.6 mm; Pannanpara recorded 75.2 mm; Melathiruchendur recorded 65.2 mm; Sivagnanapuram recorded 48.8 mm.
- Other Districts: Mahendragiri recorded 73.2 mm; Erukar recorded 62.4 mm; Paraman Kurichi recorded 58 mm; Kuttom recorded 50.8 mm. Heavy rain was also recorded in Tirunelveli and Kanyakumari districts.
- Nilgiris District: Kothagiri recorded 42.8 mm, and Nelliyalam recorded 36.8 mm.
- Dharmapuri District: Vellalapatti recorded 36.4 mm.
- Ramanathapuram District: Kanjirankudi and Pullanthai both recorded 49.2 mm.
Forecast: Next 24 to 36 Hours
The existing circulation is expected to slowly move into the Arabian Sea over the next 24 hours, where it will intensify into a low-pressure area. Rainfall will continue in Southern Tamil Nadu while this formation takes place. However, after approximately 36 hours, rainfall activity in Southern Tamil Nadu is expected to gradually decrease.
Tamil Nadu Forecast
Today, widespread rain is anticipated across Tamil Nadu. Heavy to very heavy rain is likely in districts including:
- Thoothukudi
- Ramanathapuram
- Virudhunagar
- Tenkasi
- Tirunelveli
- Kanyakumari
- Nilgiris
Moderate to heavy rain is expected in other districts:
- Interior and Northern Districts: Chennai, Thiruvallur, Kanchipuram, Chengalpattu, Villupuram, Puducherry, Ranipet, Vellore, Tiruvannamalai, Krishnagiri, Dharmapuri, Kallakurichi, and Salem. These areas may experience rain, particularly during the evening and night hours.
- Delta Districts: Cuddalore, Ariyalur, Mayiladuthurai, Nagapattinam, Karaikal, Thiruvarur, Perambalur, Tiruchirappalli, Pudukottai, and Sivaganga may also see heavy rain.
- Central Districts: Salem, Namakkal, Erode, Coimbatore, Tiruppur, Dindigul, Madurai, Theni, and Karur are expected to see widespread moderate rain, with isolated heavy showers..
Neighboring States Forecast
The system will also influence weather patterns in neighboring states:
- Kerala: Heavy to very heavy rain is likely in Kasaragod, Kannur, Thiruvananthapuram, Pathanamthitta, Idukki, Ernakulam, Kottayam, Alappuzha, and Thrissur districts, as well as the western parts of Malappuram. Moderate to heavy rain is expected in Wayanad, Kozhikode, Malappuram, Palakkad, and Kollam.
- Karnataka: Heavy rain is forecast for Bengaluru and surrounding areas, Ramanagara, and Tumakuru. Moderate to heavy rain is expected in Kolar, Chikkaballapur, Chitradurga, Davanagere, Shivamogga, Udupi, Chikkamagaluru, Hassan, Kodagu, and Dakshina Kannada. Other areas will experience dry weather.
- Andhra Pradesh: Moderate rain is expected in Central Andhra regions like Vijayawada, Guntur, Palnadu, and NTR areas. Heavy rain is forecast for Guntur, Bapatla, Prakasam, and Nellore. Rayalaseema districts, including Kurnool, Nandyal, Anantapur, Kadapa, Sathya Sai, Annamayya, Tirupati, and Chittoor, may see widespread moderate to heavy rain.
Upcoming System and Monsoon Status
In addition to the current system, another significant weather event is on the horizon. An upper air cyclonic circulation is anticipated to form around Sri Lanka and Tamil Nadu between October 20 and 21. This disturbance has a high chance of moving towards Sri Lanka and Tamil Nadu, which could potentially increase the intensity of rain, especially in districts like Cuddalore.
Regarding the Northeast Monsoon (வடகிழக்கு பறமுழை), it has been reported that the monsoon has begun. However, the official declaration from the Indian Meteorological Department (IMD) is still awaited.
Tracking Rainfall Data
If you wish to view real-time rainfall data updates, you can access the information collected by Automatic Weather Stations. Open a browser and type: https://beta-tnsmart.rimes.int/. After creating and using your user ID and password to log in, access the 'Database' option on the Disaster Management (பேரிடர் மேலாண்மை) page. From there, click on 'Rainfall amount' (மழையின் அளவு) on the left side. Rainfall data is often fully updated for all districts by 7:30 AM or 8:00 AM.
Stay safe and stay updated!
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