Late November 2025 – The polar vortex weakens and drifts south, allowing Arctic air to spill into the United States for the first time this winter, a shift that “weakened in late November and moved southward, allowing frigid air to move into heavily populated areas”[1].

Dec 4, 2025 – An Arctic air mass blankets the Plains, Midwest, Great Lakes and Northeast, exposing more than 200 million people to freezing temperatures; forecasters warn that “more than 200 million people expected to wake up to freezing temperatures this week” and project record lows of –11 °F in Des Moines and –7 °F in Cedar Rapids[1].

Dec 8‑14, 2025 – The National Weather Service forecasts a new Arctic blast for the Northeast weekend of Dec 12‑14, with wind chills below zero and potential record lows such as a projected –3 °F in Madison, Wisconsin, “temperatures in many Midwestern locations could drop 15‑25 °F below the historical average”[6].

Dec 12‑16, 2025 – Seasonal forecasters predict the coldest period of the season in mid‑December, noting that “mid‑December will bring the coldest period of the season” and that a stretched polar vortex is driving the deep‑cold outbreak across the Eastern U.S.[10].

Dec 13, 2025 – Extreme cold warnings are issued for North Dakota, West Virginia and Virginia, while freezing‑fog advisories spread to the Southeast; the NWS alerts warn residents to limit outdoor exposure as “subzero wind chills” threaten major cities[4].

Dec 27, 2025 – A pair of potent cold fronts plunge into the northern tier of the U.S. as 2025 ends, with AccuWeather’s Renee Duff stating “a pair of potent cold fronts will plunge into the northern tier of the United States as 2025 ends and 2026 begins,” bringing lake‑effect snow, widespread flight delays and over 30,000 power outages in Michigan[3].

Jan 1‑5, 2026 – The NWS six‑to‑ten‑day map shows below‑average temperatures across the Northeast, Pennsylvania, Ohio and the Great Lakes region, signaling “a bitter start to 2026” as Arctic air settles over the area[3].

Jan 12, 2026 – A powerful Arctic surge begins spilling southward into the Midwest and East, with forecasters describing “a powerful surge of Arctic air will spill southward into the Midwest and much of the eastern United States over the next 10 days,” bringing the first front through the Great Lakes on Tuesday night and gusts near 40 mph that will amplify wind chill[9].

Jan 15‑20, 2026 – The Arctic blast dominates the forecast, keeping highs in the 20s or colder through Tuesday; wind chills are expected to drop to “‑5 to ‑15 degrees” early Tuesday, prompting a Weather Impact Alert Day and a Cold Weather Advisory from the NWS[7].

Jan 19‑20, 2026 – Arctic air pushes into the South, with forecasters warning that “temperatures will be 20 to 30 degrees below average, with daytime highs staying in the 30s and 40s,” bringing cold rain, freezing rain, ice and snow to Texas, Louisiana, Arkansas and the Southeast, and urging vehicle winterization[8].

Jan 23, 2026 – A low‑pressure system forms over the southern Plains and Rockies and rapidly expands eastward, “affecting nearly 50 % of the country,” as Arctic air collides with warm, moist southern flow to produce heavy snow, ice and dangerous wind‑chill values across the Midwest, Great Lakes and Northeast[2].

Jan 24, 2026 – NASA satellite imagery tracks the storm’s extensive cloud cover and broad snow band, confirming that “the system … has moved eastward, affecting nearly 50 % of the country” and that more than a dozen states have declared emergencies, placing roughly 140 million people under alerts and causing over 8,000 flight cancellations[2].

Late Jan 2026 (early weekend) – Forecasters note that the Arctic blast could return “by early next weekend,” issuing additional Weather Impact Alert Days as sub‑zero wind chills may re‑emerge, signaling continued risk for outdoor activity and travel[7].