Millions of South Koreans began to head for their hometowns Tuesday, a day before the start of the three-day lunar New Year holiday.

Along with Chuseok (Korea's Thanksgiving Day), the Lunar New Year, which falls on Thursday, is one of Korea's biggest holidays.

Families flock en masse to their ancestral homes to hold memorial rituals for their ancestors.

This year's holiday stretches into the weekend, giving travelers an unofficial 5-day holiday period to spend with their families.

Officials estimated that about 39 million people will be on the roads during the holiday, driving or traveling in some 20 million cars.

They said cold weather is likely to cause worse-than-usual traffic snarls.

An official at the Korea Highway Corporation said the highways are already clogged with Lunar New Year traffic. Bad weather is likely to prod more people to drive their own cars.

The official also predicted heavy Seoul-bound traffic from the countryside during the holiday, with an increasing number of parents opting to visit their children's homes in the capital.