The Twin Cities and southern Minnesota refilled their snow deficit when the largest snowstorm in six years dumped a foot of snow in many locations.

The 12.4 inches recorded at Minneapolis-St. Paul International Airport on Monday brought the seasonal total to 25.3 inches, cutting the shortfall nearly in half. Normally, 30.6 inches has accumulated by this time of year, the National Weather Service said.

That had many residents spending Tuesday digging out and waiting for plows to clear the way.

Fears of tough road conditions prompted Minneapolis, St. Paul and suburban school districts to call off classes. In Edina, officials canceled school after assessing road conditions, staff availability and a shortage of substitute teachers, according to an e-mail sent to families and students.

The Minnesota Department of Transportation continued to make headway in plowing the snow-covered roads, especially in the south central and southwest part of the state, which had been under a travel advisory due to blizzard conditions Monday. Just before 8 a.m. Tuesday, that advisory was lifted, but roads remained partly ice- and snow-covered — and extreme caution was advised.

“Slower speeds are still the best option as we clean up today,” the agency said.

Interstate 35 between Owatonna and Faribault reopened. The National Guard, on standby Monday to help and house travelers in need, opened the Owatonna Armory, but only one motorist spent the night, said Master Sgt. Blair Heusdens. Nobody had to be rescued, she said.

The State Patrol had responded to 275 crashes statewide between midnight Monday and 10 a.m. Tuesday. Troopers assisted another 531 vehicles that spun out or slid off the road and 51 semitrailer trucks that jackknifed.

Mainline roads in the metro were generally snow-free but wet under sunny skies Tuesday afternoon, allowing traffic to get back to normal.

Operations at MSP were also getting back up to speed. Three of the airport’s four runways were in operation Tuesday after all were shut down for a few hours Monday afternoon when flights were grounded as crews tried to keep runways clear. The backlog of hundreds of canceled flights spilled over to Tuesday.

Cities across the metro and the state have declared snow emergencies, including Minneapolis, St. Paul, Mankato, Red Wing, Bloomington, West St. Paul and Crystal.

Southern Minnesota received the most snow, which included 17 inches in Owatonna and Winnebago, 16.5 inches in Waseca, 12.5 inches in Northfield, 12.4 at MSP, 12 inches in Falcon Heights, 11 inches in Stillwater, 9 inches in Minneapolis, but just 1.7 in Buffalo.

Monday marked the single biggest one-day snowfall since Dec. 12, 2012, when 10.5 inches fell in one day. A larger storm dumped 13.8 inches in the Twin Cities on Feb 20-21, 2011, the National Weather Service said.

The high snow totals left many side streets impassable Monday night and led to some harrowing moments for parents. In St. Paul, where school was in session Monday, many students were stranded at school well into the night as buses got stuck and could not make their rounds.

In Minneapolis, school officials called off classes on Tuesday “to recover from the significant transportation difficulties experienced after today’s severe winter weather,” spokesman Dirk Tedmon said in a statement.

Other districts closed Tuesday included Rosemount-Apple Valley-Eagan, Bloomington, Cannon Falls, Faribault, Fridley, Robbinsdale, Richfield, Spring Lake Park, Hastings and Red Wing.

Some of Monday’s snow will melt this week as temperatures will rise into the 30s on Thursday and into the low 40s on Friday, the National Weather service said.