Overview On December 1, 2025 , the Regional Meteorological Centre (RMC) in Chennai issued a forecast for heavy to very heavy rainfall in Tiruvallur and Chennai districts. This was attributed to a deep depression forming over the Southwest Bay of Bengal and adjoining north Tamil Nadu-Puducherry coasts. The forecast extended until the morning of December 2, 2025 . Key Developments Rainfall Forecast: Heavy to very heavy rain expected in Tiruvallur and Chennai districts. Affected Areas: Isolated places in Ranipet, Kancheepuram , and Chengalpattu districts are also likely to experience heavy rain. Traffic Disruptions: Heavy rains in Chennai led to road flooding and traffic slowdowns. School Closures: Several schools in Chennai allowed children to leave early due to the incessant showers. Deep Depression Location: As of 11:30 a.m. on December 1, 2025 , the deep depression was centered about 50 km east of Chennai . Movement: The system moved northwards at a speed of 3 kmph . Weakening Forecast: The deep depression is expected to weaken into a depression within 12 hours after December 1, 2025 evening. UPSC Relevance This news is relevant to the UPSC syllabus under GS1 (Geography) and GS3 (Disaster Management) . It highlights the importance of understanding weather patterns, forecasting, and disaster preparedness in the context of India's coastal regions. Important Facts Date of Forecast: December 1, 2025 Affected Districts: Tiruvallur, Chennai, Ranipet, Kancheepuram, Chengalpattu Location of Deep Depression: Southwest Bay of Bengal Speed of Movement: 3 kmph Proximity to Chennai: 50 km east of Chennai Potential Exam Questions Prelims: What was the primary reason for the heavy rainfall forecast in Chennai on December 1, 2025? Mains: Discuss the challenges faced by Chennai during monsoon season and suggest measures to mitigate the impact of heavy rainfall.