The havoc was expected to last at least three more days, forecasters said, and the Health Ministry warned of the outbreak of diseases and poisoning from car exhausts as passengers try to keep warm.
The People's Liberation Army had distributed 419,000 quilts and 219,000 cotton-padded coats to people stuck in traffic.
"Dealing with this snow disaster is even more complicated than tackling the floods of 1998 or other natural disasters we have faced," relief official Wang Zhenyao told state television. "We can mobilise millions of troops to fight floods, but at the moment we can't even fly anyone in to offer relief."
Blocked roads and railways have choked coal shipments, magnifying energy shortages that have caused power brownouts in 17 of China's 31 provinces and province-status cities. Vegetable, tea, grains and fruit crops have been destroyed.
Efforts to clear snow-clogged roads have been hampered by shortages of chemical solvents, with producers in the snow-free north unable to send shipments south. Many areas, unused to heavy snow, simply do not have the equipment to deal with it.
In Guangdong, many power plants had just two days of coal left, the official Guangzhou Daily said, and authorities were shipping in emergency supplies on a fleet of 125 cargo ships.
More than 5 million people in the central and southern provinces of Hubei, Guizhou and Jiangxi have had water supplies reduced or cut off, and parts of Guizhou have spent two weeks without power, Xinhua said.
Wen used a megaphone to tell passengers stuck at Changsha station in southern China on Tuesday that he was sorry. On Wednesday, he visited Guangzhou to offer comforting words.
"You have suffered a lot from the inconvenience," Wen told the crowd with a bullhorn as families stood around, some playing cards, some trying to entertain their children and others eating the melon seeds and clementines popular at this time of year.
Analysts said the brutal weather was a short-term blow to the economy and would stoke inflation that already has the government worried. It hit an 11-year high of 4.8 percent last year.
The National Development and Reform Commission, which steers pricing policy, said the price of cabbage and other staple vegetables has jumped by over 50 percent in snow-struck areas, and in some places rises have been much higher.
