Persistent rain in northern Japan has triggered fears of fresh landslides in the wake of powerful earthquakes which have shaken the region.
Thousands of people have been living in emergency shelters
It has also increased the misery of more than 100,000 people who have spent a third night in emergency shelters.
The death toll from the quakes, which began on Saturday, has increased to 31.
The Japanese Prime Minister, Junichiro Koizumi, has visited Niigata, 260km (160 miles) north of Tokyo, one of the worst hit areas.
Mr Koizumi toured destroyed homes and visited residents camped out in a school gymnasium.
"The victims very much want us to help them return to their normal lives as soon as possible," he said, the Associated Press news agency reported.
"I've again been made keenly aware of the need to put together response measures for both the national and local governments," he added.
The quakes have become Japan's deadliest in almost a decade.
The death toll rose on Tuesday as a 91-year-old man died in a hospital in Koide, and a 81-year-old in Ojiya died from a stroke.
Some people have been spending the nights in their cars rather than go home to unstable buildings still at risk from aftershocks that Japan's Meteorological Agency has warned would continue until the end of the week.
Conditions have been worsened by continuing rain and temperatures expected to drop below freezing.
But 76-year-old Kazuo Hotaka, staying at a school gymnasium in Nagaoka, in Nagaoka prefecture, said he was not succumbing to the cold.
"We don't have time to get sick. There's too much to do, too much to worry about, and too little information," he told Reuters news agency.
Rescuers are still looking for three people missing after Saturday's quakes, the largest of which was of magnitude 6.8.
They are a woman and her two small children who were driving home on Saturday after visiting a friend in the city of Niigata.
More than 2,000 people were injured and local hospitals say they have been overwhelmed by the number of casualties.
Much of the affected region is still without power, and authorities warn there is a desperate need for food and water supplies.
The weekend's events follow a record 10 typhoons to hit Japan this
year, including one that killed at least 80 people last week.