(CNN) -- While winter's start remains more than a month away, much of Minnesota and Wisconsin were under a winter storm warning Saturday, with some areas seeing almost a foot of snow.
As early as 10:30 a.m., 11 inches of snow had fallen in Eden Prairie, Minnesota, the National Weather Service reported.
Other Minnesota communities had seen 10 inches by midday, including New Hope, Amboy, Mankato and Montgomery, while parts of Minneapolis were blanketed by at least nine inches of snow.
In some areas, an inch of snow was falling an hour.
"Even though we get this every single year, for whatever reason, the first snow of the year appears to make everyone forget how to drive in snow," Drew Gordon, of Eagan, Minnesota, told CNN Radio. "So it's always a huge, huge mess."
Shortly after 5 p.m., the Minnesota State Patrol reported on its Twitter page that officers had responded to at least 401 crashes on Saturday, 45 of them with injuries. The agency warned drivers that conditions could worsen in the evening, as roads turned icy.
The storm also affected air travel, with dozens of flights to and from Minneapolis-St. Paul International Airport delayed or canceled.
The snow was accompanied by sustained winds blowing as high as 25 mph. The National Weather Service's warning extends through noon Sunday, with just under a foot of snow predicted in the heaviest hit areas, including Minneapolis and St. Paul.
The storm's weekend timing muted its impact on traffic and the economy. Still, as the first big snow since last spring, it managed to jolt even Minnesota residents familiar with wintry weather.
"The reality hits when you need to dig out the shovels, and the snowsuits and the boots," said Lisa Saline of Bloomington told CNN Radio. "I'm glad I don't have kids in strollers anymore, and I can hand them a shovel and have them go do the driveway."
The snow was forecast to continue into Sunday, and more might come before long, according to the National Weather Service. Temperatures were forecast to be below freezing much of next week, with a 30 percent chance of additional snow on Tuesday.
Minnesota and Wisconsin aren't the only U.S. locales experiencing wintry weather in mid-November.
"Near blizzard conditions" are forecast for Wyoming and parts of western Nebraska starting as early as Monday night, with persistent snow combining with sustained winds as high as 45 mph and gusts up to 60 mph. While the National Weather Service is predicting a break Thursday, another winter storm could barrel through that region next weekend.