Arctic Air Mass Moves Southward Friday‑Sunday The National Weather Service predicts a deep Arctic air mass will surge from the Northern High Plains on Friday, spread into the Central Plains and Ohio Valley Saturday, and reach the Mid‑South and Mid‑Atlantic by Sunday [1][2]. Forecasters expect the cold core to weaken gradually before the holiday weekend, though additional milder bursts may follow [1]. The system brings near‑record low‑maximum temperatures from the High Plains to the Mid‑Atlantic, with subzero highs forecast for major Upper Midwest cities [1][2]. This southward progression sets the stage for widespread hazardous conditions across a swath of the United States.

Temperatures Plunge 20‑30°F Below Normal Projected lows are 20‑30 °F below seasonal averages, with the greatest departures in the Northern High Plains and Ohio Valley [2]. Minneapolis is expected to dip 10‑15 °F below zero Friday‑Saturday night, while Chicago may see temperatures between 0‑5 °F below zero Saturday night, marking the coldest air of the season for both metros [1][2]. Upper Midwest and Michigan could break low‑maximum records, posting single‑digit to subzero daytime highs [1]. The extreme chill extends into the northern Gulf states and Mid‑Atlantic, where temperatures may remain below 20 °F [2].

Life‑Threatening Wind Chills and Service Disruptions Wind gusts of 20‑35 mph combined with frigid air will generate wind chills below 30 °F in the Northern Plains and Upper Midwest, and sub‑zero wind chills across the Mid‑Mississippi Valley, Ohio Valley, and Central Appalachians [2]. Cold weather advisories have already been issued for Minnesota, Wisconsin, parts of North Dakota, and Michigan’s Upper Peninsula [2]; additional extreme cold warnings cover North Dakota, West Virginia, and Virginia [1]. The United States Postal Service warns that the severe cold could disrupt mail processing and delivery in 13 states spanning the Northern Plains to the Northeast [1][2]. These conditions raise heightened risks of hypothermia and frostbite for anyone exposed outdoors.