Weather Watch: Circulation Near Kumari Sea Triggers Heavy Rain Across South India (Oct 17, 2025)
Good Morning! This is a look at the weather conditions for October 17, 2025. Please remember that this is a personal weather forecast; for official advisories, you should follow the India Meteorological Department and government sources.
Key System Update: Western Movement and Intensification
The most significant system currently impacting the region is the atmospheric upper-air circulation that was lingering over the Kumari Sea area. This system has moved slightly westward. Over the next 24 hours, it is predicted to shift further west and develop into a low-pressure area situated between the Lakshadweep islands.
It is then expected to intensify into a deep depression within the subsequent 24 hours and continue moving west into the Central Arabian Sea.
This system's movement is currently crucial for Tamil Nadu, as it is drawing in moist air from the Bay of Bengal through southeasterly and easterly winds. This process is sustaining continuous rainfall across many parts of the state.
Rainfall Review: The Last 24 Hours
Several areas, particularly coastal districts and southern Tamil Nadu, experienced significant rainfall last night and this morning.
The highest recorded rainfalls (in mm) over the past 24 hours include:
- Ramanathapuram (Karutarthakudi): 96 mm
- Tirunelveli (Melapattinam): 78 mm
- Chennai (Melavakkam): 75 mm
- Ramanathapuram (Perunali): 68 mm
- Thoothukudi (Vanaramutti): 67.2 mm
- Tiruvarur (South Kaadu): 65.2 mm
- Chennai (Uthandi): 63.6 mm
Areas like Manjolai recorded "century" rainfall yesterday, indicating extremely heavy precipitation.
24-Hour Weather Forecast (October 17, 2025)
The next 24 hours will bring widespread rain across South India, with significant moisture being pulled inland.
Tamil Nadu and Puducherry:
Widespread moderate to heavy rain is expected, often accompanied by thunder. There are chances for very heavy rain (பலத்த மழை) in eight districts.
- South Tamil Nadu: Moderate to heavy rain, with chances of very heavy rain, is likely in Kanyakumari, Tirunelveli, Tenkasi, Virudhunagar, Thoothukudi, Ramanathapuram, Theni, and Nilgiris districts.
- North and Interior Districts: Moderate to heavy rain is expected in Chennai, Tiruvallur, Chengalpattu, Tiruvannamalai, Vellore, Villupuram, Puducherry, Kallakurichi, Tirupattur, Krishnagiri, Dharmapuri, and Salem.
- Delta Districts: Moderate to heavy rain, similar to yesterday, is expected in Cuddalore, Mayiladuthurai, Nagapattinam, Karaikal, Tiruvarur, Ariyalur, Perambalur, Tiruchirappalli, Pudukottai, and Thanjavur.
- Western Districts: Moderate to heavy rain is also anticipated in Coimbatore, Erode, Tiruppur, Namakkal, and Karur.
Kerala:
Widespread moderate to heavy rain is likely, with chances of very heavy rain in some western regions. This includes areas like the western parts of Thiruvananthapuram, Pathanamthitta, Alappuzha, Kottayam, Ernakulam, Idukki, Kozhikode, Wayanad, and Kasaragod. Coastal districts, including Kollam and Malappuram, are also likely to see moderate to heavy rain.
Karnataka:
There is a potential for very heavy rain in Dakshina Kannada. Widespread moderate to heavy rain is expected in many districts (including Bengaluru, Kolar, Tumakuru, Mysuru, Chikkamagaluru, and Davanagere). However, lighter rain is predicted for Haveri, Vijayapura, and Bellary, with dry weather elsewhere.
Andhra Pradesh:
Moderate to heavy rain is forecast for Bapatla, Prakasam, Nellore, Kavali, Tirupati, Chittoor, Anantapur, and Ananthamaya. Light rain is possible only in isolated pockets in areas like Kurnool, Nandyal, Kadapa, Vijayawada, Godavari districts, Kakinada, and Machilipatnam.
Telangana:
Dry weather is largely expected, with only a slight chance of light rain around Hyderabad and its surrounding areas.
Lightning Safety Alert!
Given that many areas are expecting rain accompanied by thunder and lightning:
It is crucial that people avoid staying in exposed outdoor areas or standing under trees when lightning begins. Trees are not safe, as this is where lightning is likely to strike. If possible, seek shelter in a concrete structure. Tragically, four people died yesterday in Cuddalore district due to the impact of lightning. We encourage you to share comments on how we can improve awareness to avoid such fatalities.
Long-Range Outlook
Looking ahead, there is an anticipation for an atmospheric upper-air circulation to form in the Indonesian sea region around October 23rd or 24th. This system is expected to intensify into a low-pressure area, then a deep depression, and potentially a severe deep depression, eventually moving towards North Tamil Nadu. Although this is a long-range forecast, it is anticipated that this system could mark an interesting start to the Northeast Monsoon season after Diwali.
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Thank you, and have a nice day.
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