Cold Front Chills Eastern Warm Spell; Death Count From Weather Rises to 79 : Freeze: At least two people die overnight on the streets of Chicago. Rain sends Alabama rivers over banks. Thaw lets broken pipes flood Denver homes.

The week-old Arctic deep freeze brought an abrupt end to an unseasonable warm spell along the East Coast on Monday. In some cities, temperatures plummeted after record highs during the morning.

The number of deaths blamed on weather conditions since the cold snap began rose to at least 79. Most of those were killed in traffic accidents on slippery roads. Others died from exposure, tornadoes and fires started by overworked heaters.

In Alabama, where heavy rains preceded the cold front, rescuers in boats ferried shivering residents from flooded houses Monday. Rivers and creeks continued rising after more than a foot of rain fell from Friday night into Sunday. Hundreds of people had been evacuated there and in parts of Tennessee.

Temperatures stayed low Monday. Some examples: 16 below zero, a record, at Burns, Ore.; 34 below at Roosevelt, Utah; 27 below at Richfield, Utah; 33 below, another record, at Alamosa, Colo.; and 32 below at Big Piney, Wyo. Casper, Wyo., had warmed to 14 by midday, but the wind chill factor was 21 below. The wind chill factor early Monday in northern Indiana was 40 below.

Readings of 20 below zero or colder were reported in Idaho, Montana, Wyoming, Colorado, New Mexico, Utah and Nevada.

In Illinois, wind chill factors fell to 36 degrees below zero Monday, and residents were warned that it would get colder. At least two people died of exposure in Chicago, although shelters for the homeless reported Monday that hundreds of beds were available.

The National Weather Service said the temperature fell to 8 below zero overnight in Springfield. A wind chill factor of 36 below was reported at Midway Airport in Chicago at 8 a.m.

Sunday, after 85 hours of subzero temperatures in Denver, a brief thaw brought a flood of broken-pipe complaints as the ice that had plugged and burst water lines melted.

Scores of Utah residents were without running water, and numerous fire alarms were activated as water lines to indoor sprinklers gave way.

“I’m insane. We’ve had nonstop calls all morning,” said Eric Yost, a Salt Lake City public utilities dispatcher. “Basically, people don’t believe that, if you leave a little water running in a tap, the line won’t freeze.”

He said one caller said he had let his water run all night, then turned off the tap at 7 a.m. Within an hour, the water line froze.

A gas main rupture shut off service to 12,000 customers from Sunday through Monday at Tupelo, Miss., as freezing rain and snow flew in the area.

The arrival of the cold air in the East brought abrupt change.

New York City had a record high of 63 degrees at 6:10 a.m. Monday. Five hours later, thermometers read 43 degrees, with the mercury falling.

“It looks like cold weather for Christmas and right on through, with lows in the 20s in the mornings to the 30s in the afternoons for the rest of the week,” said Tom Grant, a meteorologist for the National Weather Service in New York.