The Northeast Monsoon, which has extended into January, is set to bring significant rainfall to Chennai and several districts of Tamil Nadu this weekend. This comes as a weather system over the Bay of Bengal has intensified into a depression and is moving towards the coast.
IMD Issues Color-Coded Alerts for Coastal Tamil Nadu
The India Meteorological Department (IMD) has placed north coastal, delta, and adjoining districts on yellow and orange alerts starting January 9. Specifically, Chennai, Kancheepuram, and Chengalpet are under a yellow alert, predicting heavy rainfall between 6 to 12 cm within 24 hours on January 10 and 11. Tiruvallur district may experience intense spells on January 11.
According to an IMD bulletin, the city and nearby areas could see light rainfall as early as Thursday, with a partly cloudy sky. Temperatures are expected to range between a maximum of 29°C and a minimum of 22°C.
Detailed Forecast and District-Wise Warnings
The depression, located about 1,270 km south-southeast of Chennai on Wednesday morning, is forecast to strengthen into a deep depression by Thursday. Officials indicate that five districts, including those in the delta region, may receive heavy rainfall on Thursday itself.
The rain activity is predicted to spread on January 9, with Nagapattinam and Tiruvarur likely to get very heavy rainfall (12-20 cm in 24 hours), warranting an orange alert. From January 10, four districts, including three in the delta, are on orange alert for very heavy rain, while eight neighbouring districts, including Chennai, are under a heavy rain warning.
The alert is expected to persist, with ten districts, including Chennai, remaining under a heavy-rain alert on Sunday, as per the IMD.
Historical Context and Expert Analysis
Meteorologists clarify that the northeast monsoon extending into January is not an unusual phenomenon. Historical data from the past 100-120 years shows this happens about one-third of the time. Between 1891 and 2024, about 20 weather systems have intensified into depressions, cyclones, or severe cyclonic storms during this period.
Weather blogger Pradeep John provided further insight, noting that except for 2023, Chennai has recorded above-normal January rainfall since 2021, with a high of 17 cm. The city, which normally averages 16 mm of rain in January, has already recorded 21.8 mm this month.
In a social media post, John stated, "Delta to Cuddalore will be the hotspot. Chennai, Kancheepuram, Tiruvallur and Chengalpet too are in the path of heavy rainfall. Heavy rain may start in the delta on Jan 9 and Chennai on Jan 10 and 11." Residents are advised to stay updated with official weather bulletins and take necessary precautions.
