Some schools in Montana took their earliest snow day in memory Monday after a blizzard dumped several feet of snow, while plunging temperatures threatened crops across other parts of the Rocky Mountains in an unusually early blast of wintry weather.

Freeze warnings were in effect in parts of Utah and Idaho, and temperatures were expected to drop into the teens and 20s in those states and Montana overnight and Tuesday morning. The cold set in with the lingering fall storm system that dumped snow for three days across much of central and western Montana, including over 4 feet on the Blackfeet Reservation and Glacier National Park.

While parts of the Rockies were dealing with frigid temperatures and unusually early snow, warnings of extreme wildfire danger emerged in eastern Utah and much of Colorado, where temperatures as high as the mid-80s, gusty winds and dry air were expected to create critical conditions.

Montana Gov. Steve Bullock has declared an emergency after the storm brought heavy, wet snow and high winds that closed roads, downed trees and caused scattered power outages. The declaration allows the state to mobilize resources to help areas that were hit.

The snow and treacherous roads led to school closures Monday in Montana towns near the Rocky Mountains that received the most snow. School superintendents in some of those communities said they couldn't remember the last time they had to cancel school this early because of snow.

"This is the first time in 23 years for sure," said Les Meyer, superintendent in the town of Fairfield. "I am sure we could have held school, but the way this storm hit and the lack of preparation for winter with all of us, it just made it a better situation for the students, parents and staff to close for the day."

Augusta Superintendent Matt Genger said schools closed down Monday because of the road conditions.

"I think our furthest student is 30 miles away," he said.

Snow drifts shut down the U.S.-Canada border crossing at U.S. Highway 89, where state transportation officials also reported that 200 head of cattle were on the roadway. A crash slowed traffic on Interstate 15 and several surrounding state highways were closed because of the snow.

The National Weather Service issued both freeze warnings and extreme wildfire danger warnings in Utah. The hard-freeze warnings in the western part of the state are expected to last until Tuesday, meaning outdoor plumbing and crops that have no protection could sustain significant damage.

The fire warning is in the eastern part of the state near Moab through Monday evening.

Like the Rockies, Nevada saw wintry weather this weekend. Less than 1 inch of snow fell in the tiny town of Winnemucca, breaking a 142-year-old record, while Lake Tahoe and some other northern Nevada towns also got snow.