Cold weather alerts are affecting 69 million people from the Midwest to the Gulf Coast, while 5 million people face new flood watches in the Pacific Northwest.

The climate phenomenon is expected to “continue for the next month or two,” national forecasters said in an update Thursday.

Detroit’s winter travel can be especially tricky due to Midwest storm tracks, which often lead to significant disruptions. The city averages 9 inches of snow each December, making road conditions unpredictable, and snow regularly remains in the forecast through the end of the year.

On Tuesday at 1:41 p.m. a winter weather advisory was released by the NWS Pendleton OR valid for Wednesday between 1 a.m. and 10 p.m. for Lower Slopes of the Eastern Washington Cascades Crest.

NOAA has officially declared the La Niña event has developed. Will this last the winter, and what are the key characteristics of a La Niña winter here in the Great Lakes region?

Cold weather exposes hidden home issues. Learn top winter risks for homeowners and steps to help avoid expensive repairs as temperatures drop.