Residents in Billings, Mont., woke up to a temperature of minus 25 degrees Fahrenheit. In Des Moines, homeowners were digging out snow from a blizzard and facing wind gusts of 45 miles per hour. Towns and cities along the East Coast were bracing for possible flooding from yet more rain. And communities near the Gulf Coast are preparing for a deep freeze.

More than 30 million Americans were under winter weather advisories on Saturday, according to the National Weather Service, from rain to high winds to heavy snow, and a large portion of the United States is expected to face the coldest conditions of winter so far.

Here is a look at some of what’s going on, region by region.

Midwest

As of Saturday morning, blizzard warnings were in effect for most of Iowa, as well as for North Dakota, South Dakota and Nebraska.

In Iowa, many rural highways were impassable, and there were several road closures in the eastern part of the state, officials said. On Friday, the Iowa State Patrol said that it had responded to 436 motorist assist calls and 72 crashes, though none were fatal.

Parts of Nebraska, Michigan, Indiana and Minnesota were under winter storm warnings, with snow expected in many areas. In the Great Lakes region on Saturday morning, more than 300,000 households were without power, according to PowerOutage.us. And bitter wind chills were expected in Illinois and Missouri.