A powerful winter stormbarreling across the northern tier of the countryhas begun unloading heavy snow across multiple states, prompting delays on roads and at airports as officials warn of dangerous travel conditions.
Tens of millions of people were under blizzard and winter storm warnings on Dec. 29 from Minnesota and Iowa to Michigan, New York and Maine,according to the National Weather Service.
More than a foot of snow was expected to fall across the upper Great Lakes region, federal forecasters said, with double that amount possible along the south shore of Lake Superior.
More:Messy weather threatens post-holiday travel across US. See forecast.

Harper Martinez, 13, plays with her 1-year-old dog, Franky, in the snow on Monday, Dec. 1, 2025, in South Bend, Indiana." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

A hawk sits on a snow covered tree at Brown Deer Park in Brown Deer, Wisconsin, Dec. 1, 2025." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

Chery Madole shops for a Christmas tree on Dec. 1, 2025, at Howell Tree Farm in Cumming, Iowa." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

Snow collects on the snout of Coco, 4, on Monday, Dec. 1, 2025, in South Bend, Indiana." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

Looking north along Southern Parkway after an early winter storm coated Louisville, Kentucky, with several inches of wet snow on Dec. 2, 2025" style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

A pair of cattle feed in a snowy field off of North Fir Road on Monday, Dec. 1, 2025, in Mishawaka, Indiana." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

After snow fell overnight, Traffic moved slowly on the 64 east bound in the Portland neighborhood of metro Louisville, Kentucky area Tuesday morning Dec. 2, 2025." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

Richard Fouts shoveled his driveway in Audubon Park the morning after an early winter storm dumped several inches of wet snow on Louisville. Tuesday, Dec. 2, 2025" style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

Jack, a Jack Russell terrier, wore a coat as he walked along 29th Street in the Portland neighborhood of metro Louisville, Kentucky area Tuesday morning Dec. 2, 2025." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

Carolyn Goodman, 74, brushes off the snow of her car in the Portland neighborhood of metro Louisville, Kentucky area Tuesday morning Dec. 2, 2025. She said she got called off of work due to the snow but was preparing to go in tomorrow." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />

Megan Brake and her Labradoodle, Nym, walk along the snow-covered sidewalks of Audubon Park on Tuesday, Dec. 2, 2025, after an early winter storm dropped several inches of wet snow on Louisville." style="max-width:100%; height:auto; border-radius:6px; margin:10px 0;" loading="lazy" />
More snow pummels Midwest. See the winter storm's impact
Harper Martinez, 13, plays with her 1-year-old dog, Franky, in the snow on Monday, Dec. 1, 2025, in South Bend, Indiana.
Weather officials told people to avoid traveling, warning those who must drive to bring a winter survival kit with them in case they get stranded. Visibility in some areas could be near zero.
"Travel could be very difficult to impossible," said the weather service office in Marquette, Michigan, warning of gusty winds up to 50 mph as 3 to 7 inches of snow falls. "The hazardous conditions will impact the Monday morning commute."
Power outages have begun piling up. More than 80,000 homes and businesses were without power in Michigan on the morning of Dec. 29,according to USA TODAY's outage tracker.
A ground stop has been issued at Detroit Metropolitan Wayne County Airport, according to theFederal Aviation Administration. Multiple airports were deicing planes on their runways, including in Albany, New York, and Burlington, Vermont.
The winter storm, which began ramping up over the weekend, is expected to peak in intensity on Dec. 29, according to the weather service.
As snow piles up across the northern U.S., the Arctic air will also march southward, breaking a dayslong heat-spell that brought record warm temperatures to several cities.
"A quick round of showers and perhaps some embedded thunderstorms will signal the arrival of the cold front as it sweeps across the East Coast and Florida, and then off into the Atlantic and the Gulf today," the national weather service said. "High temperatures today will be 30 to 40 degrees colder than yesterday across much of the Nation's midsection."
This article originally appeared on USA TODAY:Snowstorm brings 'blizzard' conditions to northern US, delaying travel