Tamil Nadu Weather: Cold Waves Set To Hit Chennai; Hosur Near Bengaluru To Dip To 10°C

After battling successive cyclones and nearly continuous rainfall for weeks, Tamil Nadu is now heading into an unusual cold phase, with weather models and independent forecasters hinting at a sharp dip in temperatures across several parts of the state.

Popular weather blogger R. Pradeep John (Tamil Nadu Weatherman) has predicted what he calls a "mini cold wave" that will grip large stretches of North and Central Tamil Nadu beginning December 12, as high-pressure dry winds start dominating regional weather.

According to his latest forecast, the KTCC belt - comprising Kanchipuram, Tiruvallur, Chennai and Chengalpattu - will begin feeling the effects of the high-pressure intrusion in the form of colder nights, lower humidity, and crisp early mornings. Minimum temperatures in the Bengaluru-Hosur belt could fall anywhere between 10°C and 12°C, marking one of the sharpest cold dips of this season. Hill stations are also expected to turn significantly colder, with Ooty and Kodaikanal likely to slip below 5°C during this period.

Pradeep John further noted that districts such as Vellore, Tirupattur, Salem, Erode, Coimbatore and Dharmapuri will see a spell of dry and chilly weather. In contrast, he said, December conditions along the west coast are set to deviate from winter norms, with coastal cities expected to "sizzle with hot weather" due to persistent dry wind flow and subsidence associated with the high-pressure system.

KTCC Drenched by Cyclone Ditwah

Tamil Nadu's shift towards colder conditions comes immediately after the state endured widespread rains triggered by Cyclone Ditwah, which affected the region between late November and early December. The cyclone - occurring soon after Cyclone Senyar in early November - left behind flooding, agricultural losses and heavy coastal impacts, even though Ditwah weakened considerably before approaching land. Its remnants hovered over the coast for nearly 72 hours, dumping large amounts of rain particularly over Chennai and surrounding districts.

A special compilation from the weather blogger shows the extent of rainfall Ditwah delivered across the KTCC region over six days:

• North Chennai: 400-700 mm
• Tiruvallur: 200-500 mm
• Central Chennai: 250-350 mm
• South Chennai: 200-300 mm
• West Chennai: 200-250 mm
• Chengalpattu: 100-250 mm
• Kancheepuram: around 100 mm

North Chennai, in particular, witnessed what the blogger described as a "once-in-ages" event, with exceptional rainfall intensity and volume. South Chennai, too, benefited from well-distributed rainfall, helping recharge groundwater across the metropolitan zone. Rainfall gradually tapered off farther inland, consistent with typical cyclone-related patterns.

Light Rainfall in Southern Districts; RMC Shares Daily Update

Meanwhile, the Regional Meteorological Centre (RMC) reported that rainfall continued at isolated pockets across Tamil Nadu on Sunday, with heavier showers occurring only in parts of South Coastal Tamil Nadu. Puducherry and Karaikal, in contrast, experienced dry weather.

Top rainfall figures recorded (in cm):

• Oothu (Tirunelveli): 8
• Nalumukku (Tirunelveli): 7
• Kakkachi (Tirunelveli): 7
• Manjolai (Tirunelveli): 7
• Kamudhi (Ramanathapuram): 4
• Papanasam, Servalar Dam (Tirunelveli), R.S. Mangalam (Ramanathapuram): 3 each

The RMC also noted that Kanyakumari recorded the highest maximum temperature of the day at 31.6°C, while Dharmapuri and Tiruttani registered the lowest minimum temperature at 18.5°C in the plains.

What Lies Ahead

With the rains fading and a high-pressure system strengthening, Tamil Nadu is now moving into a distinctly cooler phase. The next one week is expected to bring cold mornings, mild afternoons and clear skies - a sharp and welcome contrast to the turbulent weather the state has battled through the past month.