Northeast Monsoon Arrives: Heavy Rainfall Forecast for Tamil Nadu, Kerala, and South India (October 15, 2025)
Good Morning!
Welcome to this weather assessment for October 15, 2025. Based on current indicators, the possibility that the Northeast Monsoon (வடகிழக்கு பருவமழை) has commenced is high. While we wait for official announcements from the Indian Meteorological Department (IMD) or RSR, which may come today or tomorrow, the current weather structures strongly suggest the monsoon's establishment.
(Note: This is a personal weather assessment. For official public weather forecasts and information, please follow the announcements from the Indian Meteorological Research Centre (IMD) and RSR.)
Understanding the Weather Systems
The current heavy rainfall across the region is being driven by several significant weather mechanisms.
- Upper Air Circulation and Convection: We are currently observing an upper air cyclonic circulation (வளிமண்டல மேலடுக்கு சுழறச்சி) extending from the Comorin Sea and Arabian Sea regions. Deep convection is evident across these areas.
- MJO and Wave Disturbances: In the equatorial areas between the Comorin Sea and the Southern Hemisphere, there is a region showing very strong intensity, often referred to as a Westward Wind Burst (WWB). This intense area indicates the presence of the Madden-Julian Oscillation (MGO). Furthermore, this atmospheric system combines the effects of three wave disturbances: the MGO, the Equatorial Rossby Wave, and the Kelvin Wave.
- Moisture and Convergence: Yesterday and today, rain has been prevalent due to moisture-laden winds arriving from the eastern direction. Critically, atmospheric convergence (காற்று குவிதல்) is occurring, mainly concentrated over the majority of South Tamil Nadu.
These combined factors mean that the impact of rain in Tamil Nadu will be high.
Rainfall Forecast for October 15, 2025
Rainfall is expected to be widespread across South India over the next 24 hours.
Tamil Nadu & Pondicherry
Widespread moderate to heavy rain is forecast across Tamil Nadu today. Many areas in South Tamil Nadu have possibilities for heavy (கனமழை) to very heavy rain (பலத்தமழை):
- South and Interior TN: Kanyakumari and Tirunelveli districts are expected to see widespread moderate to heavy rain. Tenkasi, Thoothukudi, Virudhunagar, Madurai, Dindigul, and Sivaganga districts are likely to see widespread heavy rain, with chances of very heavy rain in isolated pockets.
- Hilly Regions: The Nilgiris district has chances for heavy to very heavy rain.
- Delta Regions: Pudukkottai, Thanjai, Thiruvarur, Nagai, Karaikal, Mayiladuthurai, Cuddalore, Ariyalur, Perambalur, and Tiruchirappalli districts are all forecast to receive widespread moderate to heavy rain, with possibilities for very heavy rain in some areas.
- North TN & Coastal Areas: Chennai, Thiruvallur, Kanchipuram, Chengalpattu, Villupuram, Pondicherry, Kallakurichi, Tiruvannamalai, Ranipettai, Vellore, and Tirupattur districts should anticipate widespread moderate to heavy rain, with chances for very heavy rain in some areas. Specifically in Chennai, morning rain, similar to yesterday, may continue until 9 or 10 AM due to the moist winds.
- Western Districts: Areas including Coimbatore, Erode, Tiruppur, Krishnagiri, Dharmapuri, Salem, Namakkal, and Karur are also likely to see widespread moderate to heavy rain.
Kerala
Rainfall was already intense yesterday, with some parts of Kottayam district recording 100 mm to 200 mm. Today, the following areas are expected to see very heavy rain: Idukki, Kottayam, Alappuzha, Pathanamthitta, Kollam, and the Western Ghats regions of Thiruvananthapuram. Other coastal districts, including Thiruvananthapuram, Ernakulam, Thrissur, Palakkad, Malappuram, Kozhikode, Wayanad, Kannur, and Kasargod, are forecast to receive widespread moderate to heavy rain.
Karnataka
Widespread rainfall, often accompanied by thunderstorms (இடியுடன் கூடிய மழை), is expected in districts such as Belagavi, Uttara Kannada, Udupi, Dakshina Kannada, Dharwad, Haveri, Shivamogga, Chikkamagaluru, Hassan, Kodagu, Mysuru, Mandya, Chamarajanagara, Bengaluru and surrounding areas, Kolar, Chikkaballapur, Tumakuru, and Ballari. Other districts may only see light rain in isolated areas.
Andhra Pradesh and Telangana
- Andhra Pradesh: Moderate to heavy rain (மிதமானது முதல் கனமழை) is anticipated in Central and South Andhra Pradesh. This includes districts such as Vijayawada, Godavari, Guntur, Bapatla, Prakasam, Nellore, Kavali, Tirupati, Kadapa, Anantapur, Satyasai, Annamayya, and Chittoor.
- Telangana: The chances of significant rain are generally lower. Light rain is expected around Hyderabad and its surrounding areas, while moderate rain may be limited to specific pockets like Jagtial, Mancherial, and Komaram Bheem.
Stay safe and follow official updates. If you haven't already, ensure you follow our channel for continuous updates and real information. We will be back with more details in the next assessment.
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