Weather Update: Delta Low-Pressure System Brings Intense Rain to South India (October 22, 2025)
Welcome back to Rainman Studio for today's weather analysis, dated October 22, 2025. This is my personal weather forecast, and it is crucial to follow official weather announcements and advice from the India Meteorological Department (IMD) and the government.
The Current Weather System
The low-pressure area (குறைந்த காற்றெடுத்து தாழ் பகுதி), which was previously situated northeast of Sri Lanka, is currently positioned near the Delta districts. We anticipate this system will move slightly northward in the coming hours, potentially moving over the Delta districts and possibly traveling close to the Cuddalore district.
A key point to note: this weather disturbance is unlikely to intensify into a cyclone (புயலாக மாறுவதற்கு வாய்ப்பு கிடையாது). It is highly probable that it will remain a well-marked low-pressure area (நன்கு அமைந்த தாழ் பகுதியாகவே செல்ல).
In the broader meteorological context, there is also a well-marked low-pressure area in the Arabian Sea. Furthermore, an upper air cyclonic circulation is present over the South Andaman regions. Interacting with these systems, a new upper air cyclonic circulation is expected to form in the Bay of Bengal within the next 24 to 36 hours.
As the current circulation moves northward over the Delta districts, westerly winds (மேற்கு திசை காற்று) have begun sweeping across South Tamil Nadu, and this westerly flow is expected to cover North Tamil Nadu completely within the next 12 hours.
Heavy Rainfall Forecast: Next 24 Hours
The next 24 hours are expected to bring widespread heavy rainfall across South India:
Kerala & Karnataka
- Kerala is predicted to see widespread heavy to very heavy rain in districts including Thiruvananthapuram, Kollam, Pathanamthitta, Idukki, Ernakulam, Kottayam, Alappuzha, Palakkad, Thrissur, Malappuram, Wayanad, Kozhikode, Kannur, and Kasaragod. Some areas may experience very heavy downpours.
- Karnataka is also under the forecast for widespread heavy rain, particularly in KGF, Kolar, Bengaluru, Chikkaballapur, Tumkur, Mandya, Ramanagara, Chamrajnagar, Mysuru, Chitradurga, Hassan, Chikkamagaluru, Udupi, Dakshina Kannada, and Kodagu. There is a possibility of very heavy rain in parts of Hassan, Chikkamagaluru, Dakshina Kannada, and Kodagu. Districts like Belgaum, Uttara Kannada, Dharwad, Haveri, Shivamogga, Davanagere, Vijayanagara, Bidar, Gulbarga, Raichur, Yadgir, Bijapur, and Bellary are expected to receive moderate rain, with heavy rain in isolated pockets.
Andhra Pradesh & Telangana
- Andhra Pradesh is anticipated to be a major hotspot, especially South Andhra Pradesh. Many parts of Tirupati and Nellore districts may experience heavy rain, with chances of very heavy rain (அதிவர கனமழை) in some areas. Heavy rain is also expected in YSR, Annamayya, Satyase Sai, and Anantapur districts. Moderate to heavy rain is forecasted further north in Kurnool, Nandyal, Bapatla, Guntur, Vijayawada, Godavari, Kakinada, Vizianagaram, and Visakhapatnam.
- Telangana districts like Hyderabad, Mahbubnagar, Narayanpet, Wanaparthy, Nagarkurnool, Nalgonda, Warangal, Yadadri, Suryapet, Khammam, Kothagudem, and Mulugu are expected to see moderate to heavy rainfall, while other districts may receive light rain.
Tamil Nadu
- Moderate to heavy rain is predicted for Nagercoil, Kanyakumari, and Nilgiris.
- North coastal districts, including Chennai, Tiruvallur, Kanchipuram, Chengalpattu, Ranipettai, Villupuram, Puducherry, Cuddalore, Thiruvannamalai, Dharmapuri, and Krishnagiri, are also expected to see moderate to heavy rain.
- The system will bring widespread moderate to heavy rain to the interior and south districts: Vellore, Tirupattur, Kallakurichi, Salem, Namakkal, Erode, Coimbatore, Tiruppur, Karur, Perambalur, Trichy, Ariyalur, Mayiladuthurai, Karaikal, Nagapattinam, Thanjavur, Dindigul, Madurai, Theni, Ramanathapuram, Thoothukudi, Tirunelveli, and Tenkasi.
- We expect the intensity of the rain in Tamil Nadu to reduce slightly after the afternoon today.
Review of Recent Rain: A Century of Showers!
The last 24 hours have recorded impressive rainfall. Rain gauges across 40 to 43 districts measured 100 mm or more ("hitting a century").
- Nellikuppam in Cuddalore district recorded the highest rainfall at 198 mm (almost 20 cm).
- Other significant recordings include Varur (Villupuram) at 171.6 mm, Pathirkupam (Cuddalore) at 167 mm, Vellum (Villupuram) at 164 mm, and Kayalpattu (Cuddalore) at 159 mm.
- Heavy rainfall was also noted in Karur (Isanaththam, 148 mm), Villupuram (Nemili, 142 mm), and Chengalpattu (Kattangulathur, 114 mm; Singaperumal Koil, 112 mm).
- Chennai's Nerkundram area recorded 102 mm.
Currently, radar images show that the majority of rain clouds are moving toward South Andhra Pradesh. However, localized heavy rain is currently occurring in parts of Chengalpattu, including Madurantakam and Tindivanam. Sriperumbudur and Poonamallee are also experiencing heavy rain. Chennai itself may see light to moderate rain in the next hour or two.
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