NEW YORK - The holiday weekend brought dangerous freezing temperatures across much of the United States, snarling everything from political campaigning to football games and travel, and knocking power out to about 350,000 customers in the Northeast and Pacific Northwest.

An Arctic blast from Canada caused temperatures to plummet across a vast swath of the country, from the Northwest into the Rust Belt, the U.S. National Weather Service (NWS) said in a Sunday bulletin.

"To highlight just how intense this outbreak of Arctic air is, over 95 million citizens fall within a Wind Chill Warning, Advisory, or Watch as of midnight tonight," the agency said.

Many spots across the southern US awoke to dangerous, sub-zero wind chills, and NWS Wind Chill products in effect for 25 states.

If you're in an impacted area, avoid outside activities if possible, and when outside, make sure you wear appropriate clothing, a hat, and gloves. pic.twitter.com/OhnUReEJSU

— National Weather Service (@NWS) January 14, 2024

In addition to dangerous wind chills extending from the Northwest through much of the central U.S., an advancing arctic airmass will support heavy lake effect snows downwind of the Great Lakes and snow squalls over the Northeast and Mid-Atlantic. pic.twitter.com/igQfnOKBir

— NWS Weather Prediction Center (@NWSWPC) January 13, 2024

Sunday could bring some of the coldest temperatures in states including Montana, South Dakota and North Dakota. There, meteorologists forecast wind chills as low as -70 degrees Fahrenheit (-57 Celsius.)

In Iowa, a powerful blizzard pulled the brakes on the ever-churning political campaigning machine as Republicans vying for the 2024 presidential candidacy canceled events due to the inclement weather.

Snow piled high on the side of every road in Des Moines at the center of the Iowa caucuses' frenzy rendered political yard signs practically useless.

Reporters spotted a pickup truck full of yard signs touting Republican presidential hopeful Ron DeSantis covered in snow with nowhere to go, sitting outside the hotel where the Florida governor is staying.

David Barker, treasurer of the Republican Party of Iowa, said the brutal temperatures forecast for Monday might test even weather-resistant Iowans.

"Iowans are pretty good at handling cold and snow, so I think we'll see good turnout, although the weather is likely to bring turnout down somewhat. It may end up being a test of how committed the candidates' supporters are," Barker said.

The cold weather's grip over Iowa is not expected to loosen until well into next week, with wind chills around -40 Fahrenheit (-40 Celsius) expected across the state "at least into Tuesday," the NWS office in Des Moines said in a post on X.

The winter storm swept across the Midwest on Saturday, cutting power to tens of thousands of households. More than 102,000 customers lost power across Pennsylvania on Sunday afternoon. Across Michigan, New York, and Wisconsin, another 86,000 customers lost power.

Maine saw historic flooding up and down the entire coast, with water swamping roads and buildings. Maine's Governor Janet Mills warned everyone to stay home.

The floods in Portland Harbor reached 14.57 feet, above the historic record set in the Blizzard of 1978. Some small buildings were swept away in the tide, media reported. Portland police said there were too many roads closed to list them all on X, the social media site formerly called twitter.

Extreme weather also impacted the Pacific Northwest and parts of the northeastern United States at the weekend. The city of Portland, Oregon, usually more accustomed to rain, was hit with snow, ice and strong winds that downed trees and knocked out power to over 160,000 customers on Sunday. Local fire officials and media reported at least two weather-related fatalities.

Thousands of flights were canceled across the country over the Martin Luther King Jr. holiday weekend due to the extreme weather conditions.

New York Governor Kathy Hochul issued a travel ban for Erie County on Saturday and the National Football League postponed the Pittsburgh Steelers vs. Buffalo Bills game to Monday due to an expected blizzard. Hochul encouraged everyone in Western New York to stay off the roads this weekend.

Forecasters expect treacherous winter weather in the middle and southern United States on Sunday, bringing a mix of snow, sleet and freezing rain.

Snow, sleet and freezing rain is also expected early this week across Texas, Arkansas, Louisiana and the Southern Appalachians, the weather service forecast. Frigid air will hit the deep South, bringing a rare 14 degree Fahrenheit weather to Atlanta by Wednesday.

The extreme weather is a reminder of the February 2021 freeze that left millions in Texas and other U.S. central states without power, water and heat for days, and a winter storm in December 2022 that almost caused the collapse of power and natural gas systems in parts of the eastern half of the country.

The storm is coming ahead of what will likely be the nation's coldest weather since December 2022, according to data from financial firm LSEG.

The Texas power grid operator ERCOT (Electric Reliability Council of Texas) on Sunday issued an appeal to the public calling for energy conservation from 6 a.m. – 10 a.m. CT (1200-1600 GMT) on Monday.

"Operating reserves are expected to be low Monday morning due to continued freezing temperatures, record-breaking demand, unseasonably low wind," the grid operator said in a statement.

(Reporting by Maria Caspani in New York; Additional reporting by Andrea Shalal and Gabriella Borter in Des Moines, Iowa, Rich McKay in Atlanta, Gnaneshwar Rajan in Bengaluru and Kanjyik Ghosh; Editing by Mark Porter and Michael Perry)