This week, the coldest air of the season — by a significant margin .
In some locations, temperatures are expected to plummet to such a low point that frostbite on exposed flesh may occur in as little as five minutes.
Highs over central and eastern Montana will struggle to get above zero today.
While daytime lows ranging from 0 to -15 degrees will be common from eastern Washington to the Upper Mississippi Valley.
Temperatures are expected to drop by 30–50 degrees below average over the next several days.
This is only the beginning of a miserable week that will grow much, much worse.