(NEXSTAR) – If you think it’s cold now, it’s about to get a whole lot worse. Almost every part of the country will see below-freezing temperatures by the week’s end, according to forecasts by the National Weather Service.

Maps (in the slideshow below) show how the arctic blast will spread from northern U.S. states all the way down south as the week progresses.

Wednesday’s forecast already shows frigid temperatures in the Upper Plains states. From there, the sub-zero temperatures creep downward.

By Thursday, the lows in Montana are as cold as negative 38 degrees. Northwest Kansas could be as cold as minus 16, and eastern Washington minus 8.

It gets even colder Friday when almost every state will see lows below freezing. Oklahoma will be zero degrees, the Texas panhandle minus 3, and Illinois negative 5.

On Saturday, Christmas Eve, the cold creeps all the way down to the Gulf and East Coast. On Christmas, things start to get ever-so-slightly better. The final map in the slideshow below, which shows the minimum forecast temperatures for Sunday, starts to show less purple — the color showing the most extreme cold conditions.

Some parts of the U.S. aren’t just going to be hit with extreme cold. The National Weather Service said a “significant blizzard” is poised to dump snow on the Upper Plains, Upper Midwest and Great Lakes Region.

Meanwhile, parts of the Northeast are still digging their way out of a weekend storm that brought up to two feet of snow.