Winter has procrastinated when it comes to delivering cold and snow, but the lollygagging is over.

A long-duration storm moving into the state late Thursday was forecast to bring several inches of snow to the Twin Cities metro area and southern Minnesota and send the mercury — and windchill readings — tumbling below zero for the first time this season, the National Weather Service said.

"There is high certainty in windchills reaching 20 to 30 degrees below zero by Saturday morning, and 30 to 40 degrees below zero by Sunday morning," the Weather Service said.

What's not quite as certain is just how much snow will fall, and where the heaviest amounts will be. A winter storm warning going into effect Thursday night and lasting until Saturday morning calls for 4 or more inches of snow across most of southern Minnesota, stretching from Worthington to Albert Lea to Mankato to Rochester and Red Wing.

Goodhue County, just southeast of the metro, could see 5 to 8 inches of snow while 4 to 6 inches is forecast for Rice, Waseca, Steele and Freeborn counties in south-central Minnesota.

A winter storm watch covers the entire metro area where 3 to 5 inches of snow could fall with heavier amounts to the east in Wisconsin and slightly lower totals to the west in places such as Olivia, Hutchinson and Redwood Falls, the Weather Service said.

But those totals could change, the Weather Service warns.

"Still some uncertainty in the overall track of the system, further forecast adjustments are expected," the Weather Service said in a Thursday advisory.

What is almost certain is that temperatures will fall to near 10 below zero by Saturday night as the storm passes through and stiff northwest winds will make it feel even colder. That combination could cause difficult travel conditions as areas of blowing snow could make roads slippery and significantly reduce visibility, forecasts warned.

The surge of arctic air flowing into the state will abruptly end the balmy start to winter that saw record highs of 55 degrees on Dec. 24 and 54 on Christmas Day in the Twin Cities. The average temperature in December was 34.3 degrees, or 12.3 degrees warmer than average, according to the Minnesota State Climatology Office.

This month has also been warmer than usual, with four days of highs of 32 or higher and a 21-degree low on New Year's Day, the coldest night in January.

The Twin Cities has made it as late as Jan. 18 before recording its first below-zero temperature of the season. That has happened on three occasions, in 1889, 2002 and 2012. In second place is Jan. 16, 1955, which will make Saturday's subzero reading the third-latest since weather records have been kept starting in the 1870s, according to the Weather Service.

The winter with the fewest readings of zero or below was in the winter of 2001-2002 with just two, the Weather Service said.