Kids in Browning, Montana, were gifted with that rare September snow day Monday after a historically early winter storm pounding parts of the West dumped four feet of snow on the town in the heart of the Blackfeet Reservation.

Barely a week after the end of summer, snow swept across parts of California, Oregon, Washington, Montana, Idaho, Nevada and Utah. The National Weather Service said temperatures in some areas were dropping as much as 30 degrees below normal.

A combination of factors contributed to the wintry blast, AccuWeather Senior Meteorologist Alex Sosnowski said.

"A storm from the Pacific Ocean, a fresh injection of cold air from northern Canada, moisture from the Gulf of Mexico and a northeast-ascending flow that squeezed extra moisture from the atmosphere produced the amazing snowfall," Sosnowski said.

Montana got the worst of it, and Gov. Steve Bullock declared a winter storm emergency. Great Falls, which normally sees less than 2 inches of snow in September, was blasted with a two-day snow total of 19.3 inches – the second-highest two-day snow total ever for any time of year.

Near-record cold was forecast for Monday night.

Dupuyer, 40 miles southeast of Browning, saw 37 inches of snow. Browning took the dubious top honors, although AccuWeather senior meteorologist Dan Pydynowski told USA TODAY less populated areas doubtlessly were slammed with more than 4 feet, but it just won't ever be measured.

"Browning Schools has cancelled all classes for tomorrow 9/30/19 to dig out from the storm," the school tweeted Sunday. It was not immediately clear whether one day of digging would be enough.

Snow drifts as high as 7 feet were reported. Sosnowski also warned that unseasonably cold conditions will delay snowmelt in some areas and halt the growing season for some farmers. The hard freeze could bring added pain to farmers already dealing snow-covered fields, he said.

Sosnowski said September snow in parts of the U.S. isn't that unusual, but the amount of snow at relatively low elevations is. The cold was also a surprising feature.

"Many daily record low maximum temperature records are possible through Monday, especially across the Northern Great Basin, Rockies and Northern California," the weather service said.

More than a foot of snow fell in parts of northeastern Washington. Spokane got the city's first recorded September snow since 1926.

The National Weather Service said Sunday was a record-breaking day in Oregon and Washington. For some locations, it was the coldest September day since 1948.

Portland International Airport tied its coldest September high temperature on Sunday, matching a temperature from 1948. The winter of 1948-49 was one of the coldest on record for the Portland area – and the airport had 22 inches of snow that winter.

"Correlation or coincidence...?" tweeted the National Weather Service office in Portland. "Probably coincidence, but I guess we'll find out."