(Missoula Current) The National Weather Service on Monday issued a winter storm warning for the Missoula and Bitterroot valleys and urged area residents to prepare for extreme subzero temperatures.

Missoula County Public Schools said Monday it was monitoring the weather and potential impacts.

Frigid temperatures are expected across the Northern Rockies, with highs remaining below zero and overnight lows up to 45 degrees below. Wind chills could make exposure life-threatening to humans, pets and livestock.

Wind gusts of 35 miles per hour are expected on top of already frigid temperatures.

“Travel could be very difficult,” the Missoula weather office said in a bulletin. “Patchy blowing slow could significantly reduce visibility. Cold wind chills as low as 30 below zero could cause frostbite on exposed skin in as little as 30 minutes.”

Cold won't be the week's only event. Snow totals of seven to 10 inches are expected in the Missoula and Bitterroot valleys. The winter storm warning takes effect on Tuesday and is expected to remain in effect through Wednesday evening.

The snow already had begun falling on Monday afternoon. While daytime temperatures reach the upper 20s on Tuesday, they will fall rapidly toward evening hours to around minus two.

Daytime highs on Wednesday will reach 8 degrees before falling to 31 degrees below zero. Thursday's high will reach minus 12 while nighttime lows will fall again to 21 below zero.

Missoula County Public Schools said recess will be held indoors whenever temperatures are below freezing and other outdoor activities may be cancelled.

"The decision to delay or cancel school due to weather conditions is based on input from local law enforcement, our bus partner Beach Transportation, and our own staff research of road conditions," said district spokesperson Tyler Christiansen.

"If a school day must be delayed or canceled due to winter weather, it is our district’s goal to provide notification to affected students, staff and families by 6:30 A.M. or sooner if possible."