Saidevo, and others: Please add to this when you can. I'll share what I know.

Thai Pongal is the Tamil harvest festival, celebrated in the month of Thai.
Here at my temple its a fun event. Some of my Sri Lankan Tamil friends take it quite seriously. Here this year it will be on the 14th of January of the Julian calender. But here it becomes crazy, because of the weather. A large pot of boiled milk is placed outside the temple. Many devotees come along and offer various grains into the large pot. The milk is heated untip it is boiled over. Then it is used as prasadam.

I am sort of the honorary guest as I am the only 'farmer' they know, because I manage the temple's vegetable garden, and I grew up on a farm in rural Alberta. This year the forecast is for about +2 Celsius. But one year it was about -30 Celsius. So people were popping in and out from the temple just to warm up. Of course many are dressed in veshtis, so it can be cold. Some wear long underwear (called Long Johns colloquially) but many don't, like me. The year it was -30 you could hardly see the pot for all the steam rising from it. At that temperature steam forms incredibly fast. So watching all these guys dancing around, giving directions, and the like is good clean fun, and funny. Most have booked off work for the morning as well, as they do take it seriously.

Perhaps, Saidevo or other Tamilians, you can elaborate, or share your stories of how this festival is celebrated locally in TN.

Aum Namasivaya