LOW Intensifying in Bay of Bengal – Tracking the Monsoon Shift
Date of Forecast: October 1, 2025
Good morning! As we step into October, the weather scenario is rapidly evolving, marked by the intensification of a major system in the Bay of Bengal and significant shifts in monsoon patterns across South India. We dive into the latest weather estimates for today and the coming week (Please note: This is a personal weather estimation; always adhere to official forecasts and advisories from the India Meteorological Department and government sources).
The Intensifying Bay of Bengal System
The focal point of today's forecast is the weather system situated over the West Central Bay of Bengal (மத்திய மேற்கு வங்க கடல் பகுதி).
Rapid Progression and Landfall:
- What began as an upper air circulation (மேலடுக்கு சுழர்ச்சி) yesterday morning has intensified into a low-pressure area (தாழ்வு பகுதி).
- It is expected to become a well-marked low-pressure area (நன்கு அமைந்த தாழ்வு பகுதி) by this afternoon.
- By midnight tonight, the system is highly likely to strengthen further into a deep depression (ஆழ்ந்த தாழ்வு மண்டலமாக).
- This system is forecast to gain strength and make landfall between Odisha and Visakhapatnam (விசாக்கப்பட்டத்திற்கும்). The expected time frame for landfall is late tomorrow night or early the day after tomorrow morning, possibly as a Deep Depression (டிப்ரஷன் ஆர் டீப் டிப்ரஷன்).
Immediate and Future Impacts:
This system is already initiating heavy rain (கனமழை) across the coastal regions of Central and North Andhra Pradesh. As it strengthens and moves, the rainfall activity will spread to Telangana & Central India.
Increased rain is expected in West Bengal, Odisha, the western parts of Uttar Pradesh, and Central Indian regions.
Dual Influence: The Arabian Sea System
Simultaneously, a well-marked low-pressure area is currently positioned off the Gujarat coast. This system is anticipated to move west-northwest (மேற்கு வடமேற்கு திசையில நகர்ந்து), strengthen, and proceed westwards into the Arabian Sea as a low-pressure trough/depression (தாழ்ந்த தாழ்வு மண்டலமா).
The combined effect of these two weather systems is currently making the Southwest Monsoon vigorous (வீரியமடைந்து), leading to rain in many areas today.
Transition to Northeast Monsoon: Focus on Tamil Nadu
The coming weeks mark a crucial transition period, especially for Southern India:
- SW Monsoon Withdrawal: The Southwest Monsoon is expected to initiate its complete withdrawal (முற்றிலுமா விலகுறதுக்கு வாய்ப்புகளை உருவாக்கி கொள்ளும்) after October 11th, starting from Central India.
- Increase in Convective Rains: When the Bay of Bengal system nears the Odisha coast (tomorrow), the convective rain (வெப்பச்சரண மழை) in Tamil Nadu is expected to gradually increase. While the Southwest Monsoon wind strength is currently reduced, it will begin to ease its strength after tomorrow. Convective rain is set to start in the next 24 hours, becoming widespread for two days beginning Friday (வெள்ளிக்கிழமையில இருந்து). Widespread convective rain across Tamil Nadu is expected to start from October 3rd.
- Wind Shift (Post-Oct 9): From October 9th, interior Tamil Nadu will begin experiencing changes in East-West winds. A wind discontinuity (காற்றின் முறிவு பகுதி) will form over Central Tamil Nadu, which is expected to bring widespread thunderstorm rain (இடியுடன் கூடிய வெப்பச்சன மழை), with possibilities of heavy rain (கனமழை கூட), across interior districts of South, North, West, and Central Tamil Nadu.
- Full Eastward Flow (Post-Oct 13): After October 13th and 14th, the rain coming from the West will completely stop, and the wind flow will shift entirely to the East (கிழக்கிலிருந்து). At this point, rain clouds will move from the East and begin registering over the coastal districts of Tamil Nadu. There is also an anticipation of a system potentially forming near Sri Lanka around the 13th or 14th, which warrants monitoring due to the long-range nature of the forecast.
Today's Regional Rain Forecasts (October 1, 2025)
| Region | Expected Rainfall | Key Districts/Areas |
|---|---|---|
| Andhra Pradesh | Moderate to Heavy Rain: Central AP (Vijayawada, Krishna, Godavari districts). Heavy to Very Heavy Rain (கனமழை முதல் வளத்தமழை): North Coastal AP (Srikakulam, Vizianagaram, Visakhapatnam). Light to moderate rain in Rayalaseema (Tirupati, Nellore, Kadapa). | The increased rain in AP is expected to continue for two to three days, potentially up to five days maximum. |
| Telangana | Rain starts in the far western parts. Moderate to Heavy Rain: Kothagudem, Mulugu, Jayashankar, Peddapalli, Mancherial, and Komarambheem districts. Light rain in other districts, including Hyderabad. | Rain will gradually increase starting tomorrow and continue for two to three days, potentially up to five days maximum. |
| Kerala | Moderate to Heavy Rain (மிதமானது முதல் கனமழை): Western parts of Kasaragod, Kannur, Kozhikode, Wayanad, Idukki, Pathanamthitta, Kollam, and areas bordering the Western Ghats in Thiruvananthapuram. Light rain in coastal areas like Malappuram, Thrissur, Ernakulam, and Kottayam. | |
| Karnataka | Moderate to Heavy Rain: Coastal areas (Goa, Uttara Kannada, Udupi, Dakshina Kannada, Kodagu). Light to moderate rain in other districts, including Bangalore. | |
| Tamil Nadu | Light or Moderate Rain (லேசான மழை அல்லது மிதமான மழை): Expected in some parts of Chennai, Tiruvallur, Kanchipuram, Chengalpattu, Vellore, Kallakurichi, Villupuram, Pondicherry, Delta regions (Thiruvarur, Pudukkottai), Southern districts (Tenkasi, Manjolai areas of Tirunelveli), Kanyakumari, Valparai, and Nilgiris districts. |
Stay informed and follow us daily for updated forecasts as these complex systems develop.
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