Weather Update: Heavy Rains Across South India, Monsoon Shifts, and Cyclone Watch!
Good morning, weather enthusiasts! This post brings you a crucial weather update for September 17, 2025, based on the personal weather analysis from Rainman Studio - MAS Rainman Venkateshan. While this is a personal forecast, it's always advisable to follow official advisories from the Indian Meteorological Department and government sources.
Current Atmospheric Conditions
We're seeing several active weather systems:
• A low-pressure area continues to persist in the South China Sea.
• The upper air cyclonic circulation over the Andaman Sea has moved slightly north.
• An upper air cyclonic circulation remains over Vidarbha, extending to parts of Jharkhand and Chhattisgarh.
• Another upper air cyclonic circulation continues between Uttar Pradesh and Delhi.
• The upper air cyclonic circulation over Assam has weakened.
• A North-South Trough, an atmospheric lower-level circulation, is currently passing through interior Karnataka and Tamil Nadu.
Southwest Monsoon: Withdrawal and Strengthening
The Southwest Monsoon has already begun its withdrawal process. Yesterday, it withdrew from parts of Rajasthan, Punjab, Haryana, and some areas of Gujarat. Today, further withdrawal is expected from more parts of Gujarat and Rajasthan.
Interestingly, due to the influence of the low-pressure area in the South China Sea, drawing moist air from the equatorial westerlies, and the circulation over the Bay of Bengal, the Southwest Monsoon is expected to strengthen over Kerala, Karnataka, Andhra Pradesh, Telangana, and Central India. This strengthening will cause a temporary lull in the monsoon withdrawal process, which is expected to resume after September 30.
Upcoming Significant Weather Events
Keep an eye on these developments:
• Over the next two to three days, a powerful cyclonic system is anticipated to form in the South China Sea.
• Around September 22, the upper air cyclonic circulation in the Bay of Bengal is expected to strengthen, potentially intensifying into a depression, deep depression, or even a marginal cyclone. This system is predicted to move between Bhubaneswar and West Bengal.
Rainfall Forecast for the Next 24 Hours
Here's a regional breakdown of what to expect:
• Kerala: Widespread moderate to heavy rain, with very heavy rain possible in the Western Ghats and northern Kerala.
• Karnataka: Heavy rain is likely in Dakshina Kannada, Udupi, Uttara Kannada, and Goa. Most parts of interior Karnataka will experience widespread moderate rain, and Bengaluru has a high chance of rain today.
• Andhra Pradesh: Rayalaseema and Hyderabad are expected to see widespread moderate to heavy rain. Central and North Andhra Pradesh might receive light rain in some areas.
• Maharashtra & Central India: Widespread moderate to heavy rain in Maharashtra, and isolated moderate rain in parts of Central India.
• Uttar Pradesh, Bihar, West Bengal & Northeast States: Most areas are likely to experience moderate rain, with heavy rain in isolated spots.
Tamil Nadu Specific Forecast: The North-South Trough moving through the state will bring widespread convective rainfall.
• South Tamil Nadu (Nagercoil, Kanyakumari, Tirunelveli, Thoothukudi, Virudhunagar, Ramanathapuram, Sivaganga, Madurai, Theni, Dindigul): Expect moderate to heavy rain to continue today.
• Central Tamil Nadu (Namakkal, Karur, Trichy, Pudukkottai, Sivaganga): Moderate to heavy rain is likely.
• Coastal Areas: Coastal Pudukkottai, Thanjavur, coastal Sivaganga, and some northern parts of Ramanathapuram district could experience very heavy rain.
• Delta Districts (Tiruvarur, Nagapattinam, Karaikal, Mayiladuthurai), Ariyalur, Perambalur: Widespread thunderstorms are expected.
• Western Ghats (Nilgiris, Valparai, Kodaikanal): Moderate to heavy rain is forecasted.
• Erode, Tiruppur, Dindigul, Karur, Namakkal, Salem: Widespread thunderstorms are probable, with heavy rain in some areas.
• Dharmapuri: Heavy to very heavy rain is possible.
• Krishnagiri, Tiruppathur, Vellore, Tiruvannamalai, Villupuram, Kallakurichi, Puducherry: Widespread thunderstorms are likely.
• Chennai, Tiruvallur, Kanchipuram, Chengalpattu: Moderate to heavy rain is expected, particularly towards the coast. Some parts of Ranipettai, Kanchipuram, and Chengalpattu could even receive very heavy rain, similar to yesterday.
• Coimbatore & Tenkasi: Only light rain is expected in these districts.
Northeast Monsoon Outlook
Looking ahead, the Northeast Monsoon is anticipated to commence around October 18-20. A detailed preview of this monsoon will be provided in the first week of October.
Important Reminder
Remember that weather forecasts are subject to change. For the most up-to-date information, it's recommended to follow daily weather reports.
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