INDIANAPOLIS — Dangerously cold temperatures blamed for at least a dozen deaths have wreaked havoc across a wide swath of the U.S., freezing a water tower in Iowa, halting ferry service in New York and leading officials to open warming centers even in the Deep South.

The National Weather Service issued wind chill advisories and freeze warnings Tuesday covering a vast area from South Texas to Canada and from Montana through New England.

In Montana, forecasts portend a much less dramatic week on both sides of the mountains.

A full 3 ½ feet of snow were recorded Wednesday through Saturday on the south edge of Glacier National Park, and wind chill temperatures in northern and eastern Montana dipped to as low as 50-60 below zero.

A winter weather advisory was still in effect through Tuesday evening on the Blackfeet Reservation, where U.S. Highway 2 from Marias Pass to Cut Bank and a 25-mile stretch of U.S. Highway 89 south of Browning were closed for several hours in the morning due to blizzard conditions. All roads were reopened by early afternoon.

Glasgow dropped below zero on Christmas Eve and didn’t climb back above it until 2 p.m. on Tuesday, a stretch of nine days.

The extreme cold was pushing steadily to the east into the Dakotas and Minnesota. Eastern Montana should escape another brief Arctic blast on Wednesday that will hammer the Upper Midwest again.

Corby Dickerson of the National Weather Service in Missoula said no significant snow is expected in western Montana until the weekend, if then.

An inversion will keep temperatures in the western valleys in the 20s for a day or two, although slightly higher elevations won’t be so blanketed. They should see blue skies and temperatures approaching or above the freezing mark.

“Most of the ski hills in the area are going to be quite beautiful,” Dickerson speculated.

In Missoula “it looks like we’ve got enough of a system that’ll make it in by Friday afternoon where we should see things warm up and push temps above the freezing mark, although probably briefly,” he said.

The four days of snowfall that peaked on Friday brought 10 ½ inches to Missoula at the airport; 11 to 16 inches in and around Kalispell; 31 inches at Seeley Lake, and 36 east of Bigfork. They were all topped by Nyack, between West Glacier and Essex, where 42 inches were recorded in the period that ended on Saturday. 

Indianapolis early Tuesday tied a record low of minus 12 degrees Fahrenheit for Jan. 2 set in 1887, leading Indianapolis Public Schools to cancel classes. And the northwest Indiana city of Lafayette got down to minus 19, shattering the previous record of minus 5 for the date, set in 1979, the National Weather Service said. After residents there began complaining of a hum, Duke Energy said it was caused by extra power surging through utility lines to meet electricity demands.

"The temperatures are certainly extreme, but we've seen colder," said Joseph Nield, a meteorologist in Indianapolis, noting that the all-time low temperature in Indiana was minus 36 in 1994.

Nevertheless, the cold is nothing to trifle with, forecasters warned.

With Chicago-area wind chills expected between -35 and -20 degrees, forecasters warned of frost bite and hypothermia risks and urged residents to take precautions, including dressing in layers, wearing a hat and gloves, covering exposed skin and bringing pets indoors.

In Tennessee, corrections officials at a maximum security prison were using portable heaters and extra blankets to keep inmates and employees warm. The facility lost hot water pressure Monday, causing its boiler to go offline. A spokeswoman didn't provide a timeline for its return.

Atlanta hospitals were seeing a surge in emergency room visits for hypothermia and other ailments as temperatures plunge well below freezing. The temperature in Atlanta fell to 13 degrees before dawn in Tuesday.

"We have a group of patients who are coming in off the street who are looking to escape the cold — we have dozens and dozens of those every day," said Dr. Brooks Moore, associate medical director in the emergency department of Grady Health System, which operates Georgia's largest hospital in Atlanta.

The cold is blamed in at least 12 deaths in the past week.

Police in St. Louis said a homeless man found dead inside a trash bin Monday evening apparently froze to death as the temperature dropped to negative 6 degrees. Sheriff's officials in Fond du Lac County, Wisconsin, said a 27-year-old woman whose body was found Monday evening on the shore of Lake Winnebago likely died of exposure.

The Milwaukee County Medical Examiner's Office said two men whose bodies were found Sunday showed signs of hypothermia. Police believe the cold weather also may have been a factor in the death of a man in Bismarck, North Dakota, whose body was found near a river.

Warming shelters were opened across the South as freeze watches and warnings blanketed the region, including hard freeze warnings for much of Louisiana, Mississippi and Alabama. Temperatures fell to 8 degrees near Cullman, Alabama, and 20 degrees in Mobile, Alabama. Georgia saw one of its coldest temperatures of the winter: 2 degrees shortly before dawn at a U.S. Forest Service weather station at Toccoa, Georgia.

Plunging overnight temperatures in Texas brought rare snow flurries as far south as Austin, and accidents racked up on icy roads across the state. In the central Texas city of Abilene, the local police chief said more than three dozen vehicle crashes were reported in 24 hours.

And in Savannah, Georgia — where the January's average high is 60 degrees — the temperature hovered at 30 at noon Tuesday, cold enough for icicles to dangle from the ornate wrought-iron fountain in Forsyth Park at the edge of the city's downtown historic district. The city could see up to 2 inches of snow and sleet on Wednesday, the first measurable snow since February 2010.

Arctic temperatures also caused problems on waterways, for both waterfowl and boats. Firefighters in Richmond, Virginia, freed a swan that was stuck for hours Monday in the middle of a frozen pond.

In New York, transportation officials suspended the Newburgh-Beacon commuter ferry service on Tuesday because of icy conditions on the Hudson River. Just north, the city of Poughkeepsie saw a record-breaking low of minus 10 degrees on New Year's Day.

Now forecasters are tracking a storm that could bring snow and ice to the East Coast later this week.

Missoulian reporter Kim Briggeman contributed to this story.