Fog, mist to persist across T.N. as winter conditions extend into mid-February

Various districts of the State may continue to witness moderate fog and mist throughout the week, with dry winter conditions extending till mid-February.

On Monday, foggy conditions were observed in interior and northern parts of the State, including Chennai and its outskirts, leading to reduced visibility in some pockets during the early morning hours.

Officials of the Regional Meteorological Centre said winter conditions had extended into late February in recent years, owing to the spillover of the Northeast monsoon into January. The Northeast monsoon for 2025 retreated from the State on January 19 this year.

The RMC has forecast shallow to moderate fog over pockets of districts including Ranipet, Vellore, Theni, Tirupattur, Dharmapuri, and the Nilgiris till February 13. Many other districts, including Salem, Erode, Dindigul, Chennai, and its surrounding districts, are likely to witness mist throughout the week.

V.R. Durai, Director, Area Cyclone Warning Centre, RMC, said dense fog was observed in some places such as Chennai’s outskirts, where the visibility dropped to 300 metres on Monday. A visibility of 1,000 metres was reported in the vicinity of the Chennai Airport between 6.30 a.m. and 7.30 a.m.

The prevailing dry weather and clear skies in most parts of the State this February are expected to enhance night-time radiational cooling, leading to a drop in the minimum temperature by 1-2 degrees Celsius below average in some places till February 13.

In coastal areas, easterly winds from the Bay of Bengal are bringing in moisture, and the combination of high moisture content and temperature inversion – where a layer of warm air traps cooler air near the surface – is creating ideal conditions for fog formation. Light and calm winds are further aiding fog development, Mr. Durai said.

Last year, the coastal parts of the State experienced similar foggy conditions in February due to the delayed withdrawal of the Northeast monsoon. At Chennai Airport, visibility dropped to the lowest level of 200 metres at 7.30 a.m. on February 8. Moderate fog and poor visibility of 800 metres-1,000 metres were observed on several days till February 25.

The RMC has forecast that dry weather could cause a gradual rise in the maximum temperature in parts of the State till the weekend.