Heavy Rain Alert for South India: Weather Update October 13, 2025

Welcome to this essential weather forecast update from Rainman Studio! Today, October 13, 2025, we are tracking significant weather systems that are bringing widespread moderate to heavy rainfall across South India.

For reliable weather forecasting, we always advise following advisories issued by the Indian Meteorological Department (IMD) and government institutions.

The Science Behind the Rain

The current weather dynamics are heavily influenced by the MGO (Madden-Julian Oscillation) and R (Rossby) oscillations, which are presently active over parts of the Indian Ocean.

We are monitoring two key atmospheric structures:

1. A low-level atmospheric cyclonic circulation (vatliimandala melaedukku suzharchi) extending from the Kanyakumari Sea (Kumari Kadal) region up to the West Arabian Sea.
2. A weak low-level atmospheric cyclonic circulation persisting near North Tamil Nadu and South Andhra Pradesh.

The current rainfall affecting Interior Tamil Nadu, Karnataka, Kerala, and Andhra regions is due to the interaction between these systems, including wind shear, friction, and atmospheric instability (kaatrin disai verupadu matrum kaatrin uraivu kaatrin neechamattra thanmai).

Furthermore, expect a change later today (afternoon/evening) as the arrival of easterly winds (kilakku thisai kaatrin varugai) begins in the lower layers (starting at 700 HP and streamlining at 850 HP). This shift suggests that rain associated with these easterly winds may begin in the coastal districts over the next one or two days.

Detailed 24-Hour Rain Forecast

Here is the breakdown of expected rainfall across key states for the next 24 hours, starting today:

Tamil Nadu & Puducherry

Tamil Nadu is expected to see widespread moderate to heavy rain today.

• Moderate to Heavy Rain (Widespread): Nagercoil, Kanyakumari, Tirunelveli, Tenkasi, Thoothukudi, Virudhunagar, Ramanathapuram, Madurai, Dindigul, Sivaganga, Pudukkottai, Perambalur, Tiruchirappalli, Karur, Namakkal, Salem, Kallakurichi, Erode (including surrounding areas), Tiruppur, Coimbatore, and Nilgiris districts.
• Widespread Moderate to Heavy Rain (North TN): Dharmapuri, Krishnagiri, Salem, Tirupattur, Vellore, Tiruvannamalai, Villupuram, Ranipet, Tiruvallur, and Kancheepuram districts.
• Heavy to Very Heavy Rain Potential: Some areas adjoining the Western Ghats in Kanyakumari, as well as specific regions like Valparai, Sholayar, Theni, Cumbum, Bodinayakanur, and Kodaikanal and their surroundings.
• Delta Districts: Heavy rain is likely in Cuddalore, Ariyalur, Tiruvarur, Nagapattinam, and many parts of Thanjavur district.
• Coastal/Light Rain: Light to moderate rain is possible in isolated pockets in coastal Cuddalore, Chennai, Chengalpattu, Puducherry, eastern parts of Mayiladuthurai, Karaikal, and coastal areas of Nagapattinam district.
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Kerala

Many districts in Kerala will experience moderate to heavy rain with thunder.

• Heavy to Very Heavy Rain: Expected in Idukki, western Pathanamthitta, western Kollam, and areas adjoining the Western Ghats of Thiruvananthapuram.
• Moderate to Heavy Rain with Thunder: Forecasted for most parts of Thiruvananthapuram, Kollam, Pathanamthitta, Alappuzha, Kottayam, Ernakulam, Thrissur, Palakkad, and Malappuram districts. Heavy rain is also likely in the western areas of Malappuram and Nilambur, which border the Western Ghats.
• Light Rain: Only light rain is anticipated in a few parts of Wayanad, Kozhikode, Kannur, and Kasaragod districts.
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Karnataka

Rain is expected today across large parts of Karnataka.

• Widespread Moderate to Heavy Rain: Areas including Bengaluru, KGF, Kolar, Chikkaballapur, Ramanagara, Tumkur, Mandya, and Hassan.
• Light Rain: Light rain is expected in Chitradurga, Koppal, Karavali regions (Uttara Kannada, Shivamogga, Udupi), and some parts of Kalyana Karnataka.
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Andhra Pradesh

Andhra districts will experience widespread rain.

• Heavy to Very Heavy Rain: Specifically expected in Chittoor district.
• Widespread Moderate to Heavy Rain: Likely in Nellore, Kavali, Tirupati, Annamayya, YSR Kadapa, Nandyal, Kurnool, Anantapur, Satya Sai, Vijayawada, Guntur, Visakhapatnam, Srikakulam, Manakappalli, Rajahmundry, Kakinada, Machilipatnam, and many areas, including the Godavari region.
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Telangana

Telangana is also expecting significant rainfall.

• Heavy Rain: Predicted for Wanaparthy (Vanaspati), Warangal, Mulugu, Mahabubabad, Kothagudem, and Khammam districts.
• Light to Moderate Rain: Expected in other districts, including Hyderabad.
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