The snowstorm is happening much earlier than normal, forecasters say.

Some areas have seen temperatures drop 50 degrees in 24 hours.

Parts of the nation that were mowing lawns this week broke out snow shovels Thursday as a sprawling storm sweeping across the West threatened to develop into an "all-out blizzard" over the Dakotas, where a blizzard warning has been issued.

AccuWeather meteorologist Geoff Cornish said some parts of Montana have seen a foot or two of snow. More areas could see that much as the storm eases east, he said.

"It's going to be really cold out there, and a spectacular winter storm for early October, much earlier than normal," he said. "Nasty winds are going to be buffeting the northern Plains on the backside of this storm."

Some areas saw temperatures drop 50 degrees in 24 hours. Billings, Montana, fell from 74 degrees to 25 degrees. Denver, which saw a high temperature in the 80s Tuesday, saw temps plummet into the 20s. The city was forecast to get its first accumulation of the season Thursday, 1 to 3 inches.

More record-breaking:It was the hottest summer on record for the Northern Hemisphere

Spokane International Airport recorded 3.3 inches of snow Tuesday, breaking a record set almost 40 years ago. Thousands were without power in the area as the heavy wet snow took down tree limbs and power lines, Avista Utilities said.

"#avista crews working to restore power to areas that are still without. A lot of progress has been made in 24 hours," the company tweeted.

Heavy snow fell on the northern Rockies and moved southeastward along with a charge of cold air, AccuWeather said. Winds were expected to increase into Friday, and blowing and drifting snow could force some roads to close down as conditions deteriorate, AccuWeather said.

"Crippling blizzard likely Friday into Saturday morning for much of eastern ND & Red River valley," tweeted the National Weather Service in Grand Forks, North Dakota.

"One to three feet of snow is expected, with locally higher amounts," the weather service said, noting that one of the storm's impacts will be "several days of impossible travel."

The National Weather Service in Bismarck, North Dakota, warned that snow had made roads slippery Thursday: "Use caution if on the roads today!"

In California:Power restored to 50,000 homes, businesses, but many still in the dark.

And down South:Blistering heat and little rain cause a 'flash drought' in the South