Millions of Americans are under weather warnings or advisories today as the U.S. braces for a new winter storm this week. A freeze warning is in place for several California counties, according to the National Weather Service (NWS).

The National Weather Service has issued a winter weather advisory for the Sacramento area until Sunday at 4 p.m., with wind gusts up to 55 mph and a 70% chance of rain, and the Placerville area expecting 4 to six inches of snow.

A pair of quick-moving weather systems will sweep through the Great Lakes, New England and the Northeast. Travel could become challenging at times. Let's break it down.

A breezy and mild Monday is in store for southern New England, with winds gusting between 25 and 35 mph, and temperatures reaching the upper 30s to low 40s. Dry conditions will persist, but a cold front arriving early Tuesday morning will bring another blast of cold by Thursday morning. Expect snow squalls between 4 a.m. and 9 a.m.

Boston and the rest of New England have been dealing with well below-average temperatures, in some cases falling 20 degrees, as an expansive mass of Arctic air spreads across the eastern half of the United States. This cold surge is making our region this week feel colder than Anchorage, Alaska, which is topping out at 36 degrees.

The coldest temperature ever recorded was Feb. 9, 1934, when it fell to 17 degrees below zero, according to National Weather Service records, which go back to 1904. More: How much snow did Rhode Island get? See snowfall totals for Providence, Newport, Warwick

What's likely to be the coldest weather of the season will roll into Southern New England early next week. The National Weather Service is forecasting overnight low temperatures Monday and Tuesday "mainly in the single digits" with some "below zero ...

Multiple states in the Great Lakes and Northeast are preparing for consecutive snow squall disturbances this week.

A magnitude 3.8 earthquake struck off the coast of New England mid-Monday morning, sending tremors across the region. The United States Geological Survey confirmed the quake and said it hit offshore at 10:22 a.m. about 8 miles east of Portsmouth, New Hampshire, and about 6 miles southeast of York Harbor, Maine.

Millions of Americans are under weather warnings or advisories today. Follow Newsweek's live blog for updates.

Forecasters say Canadian clippers will bring gusty winds and snow squalls across parts of the nation this week.