Chennai has witnessed a remarkably wet start to the year 2026, with significant rainfall in the first week pointing to a continuing shift in the city's traditional weather patterns. The first six days of January alone have delivered 30mm of rain to parts of the city, already surpassing the monthly average and marking the third consecutive year of excess January rainfall.
A Departure from the Driest Month
January is historically one of Chennai's driest months, with a normal average of just 16mm of precipitation. However, data from the India Meteorological Department (IMD) reveals a clear deviation from this norm. The Chennai subdivision has already recorded 21.8mm of rainfall since January 1, which is a staggering 246% above the normal level for this period. Specific observatories reported 30mm in Nungambakkam and 8.5mm in Meenambakkam.
More Rain on the Horizon with IMD Alerts
The wet spell is far from over. A well-marked low-pressure area, which formed over the southeast Bay of Bengal and adjoining equatorial Indian Ocean on Tuesday, is likely to intensify into a depression. This system is expected to bring more substantial rainfall to the region later this week.
In response, the IMD has issued a series of alerts. A yellow alert has been declared for heavy rainfall of 6-12cm in 24 hours for Chennai, Kancheepuram, and Tiruvallur districts on January 10 and 11. More severe orange alerts were issued for five delta districts on January 9, and for three northern districts, including Chengalpet, on January 10, warning of heavy to very heavy rainfall between 12-20 cm within a day.
As the system intensifies and moves closer to Tamil Nadu, the forecast predicts heavy rain for seven districts adjoining the delta region on January 9. This will be followed by heavy rain in 12 districts, including Chennai, on January 10, and in 11 districts, including Chennai, on January 11.
Experts Note a Recurring Trend
IMD officials acknowledge that excess rainfall in January is not an entirely unusual phenomenon. B Amudha, Deputy Director General (Additional Charge) at the Regional Meteorological Centre, explained, "The normal date of cessation of north-east monsoon rains over southeast peninsular India is December 30. Based on data from the past 100-120 years, the monsoon extended into January on about one-third of occasions."
Weather blogger Pradeep John highlighted the recent trend, noting, "January recorded a huge excess of 166.2mm in 2021, 90.3mm in 2022, and 65.2mm in 2024. This year too, Chennai already recorded excess rainfall due to the New Year spell, and with another spell likely between January 10 and 12." This consistent pattern over recent years strongly suggests a shift in the city's rainfall calendar.
For Wednesday, the IMD bulletin predicted dry weather with mist or haze during early morning hours for the city and suburbs. Partly cloudy skies are expected to keep the maximum temperature around 29°C and the minimum between 23-24°C, offering a brief respite before the next wave of rain arrives.
