December in the US may see some of Earth's most extreme cold

While exact forecasts are still pending, experts increasingly agree that December will bring unusually cold temperatures to many parts of the United States. The National Weather Service's Climate Prediction Center indicates that colder-than-average conditions are expected primarily in the northern and northeastern regions. Some meteorologists suggest that shifts in the polar vortex could deliver some of the planets harshest cold air to the U.S.

Climatologist Judah Cohen, a research scientist at MIT, noted in an email that "early December cold may just be a precursor, with the most severe conditions likely in mid-December." According to Cohens climate model, the largest area expected to experience extreme cold stretches from the Canadian Plains to the U.S. East Coast during the third week of December.

Snowfall remains uncertain, as predicting snow-producing systems more than a few days in advance is difficult. However, the presence of cold air is a necessary component for snow to occur.

Polar Vortex Status

Weather Trader meteorologist Ryan Maue reports that the main body of the polar vortex will largely remain over Canada for the next 710 days. Maue continues to track the risk of polar vortex intrusions into the Lower 48 states as December progresses.

Cohen emphasized that the interaction of large-scale atmospheric patterns, including the polar vortex and sudden stratospheric warming events, will influence the severity and duration of cold conditions. He acknowledged, however, that uncertainty remains about the exact behavior of the polar vortex.

Temperature Outlook

Although the most extreme cold is expected later in December, widespread below-average temperatures are anticipated next week from the western High Plains to the East Coast. Southeastern states may see near-average conditions, while Florida is expected to remain relatively warmer, according to the National Weather Service.

The coldest conditions are forecast for the Midwest on Monday, December 1, and Tuesday, December 2. Highs may only reach the teens to mid-20s, with lows dropping to zero or below in northern Missouri and Illinois. Subzero overnight temperatures are also possible from eastern Montana to North Dakota.

Overall, the northern-central U.S. is likely to experience unusually cold weather during the first week of December.

Analysis: December Cold Outlook and Key Uncertainties

Based on current guidance from the National Weather Service and multiple meteorologists, the signal for colder-than-average conditions across much of the United States in December is strengthening. The highest confidence remains focused on the northern and northeastern regions, with below-average temperatures expected to expand from the western High Plains to the East Coast during the first week of the month.

Model output cited by climatologist Judah Cohen indicates that early December cold may precede a more significant outbreak in mid-December. The greatest risk for extreme cold appears during the third week of December, with a broad corridor from the Canadian Plains to the U.S. East Coast potentially affected.

The polar vortex is expected to remain largely centered over Canada in the near term, according to Weather Trader meteorologist Ryan Maue. However, the potential for southward intrusions into the Lower 48 will continue to be monitored as December progresses, especially in relation to large-scale atmospheric interactions.

Snowfall projections remain limited due to forecast uncertainty beyond short time ranges. While cold air will be present, the development of snow-producing systems cannot yet be determined. At this stage, temperature trends are clearer than precipitation outcomes.

In summary, the available data supports an unusually cold start to December across the northern-central United States, with the possibility of more severe cold later in the month. Confidence in timing and intensity will improve as atmospheric patterns become better defined.

Sources:

• Some of Earth's most extreme cold may be headed for the US in December