December 2025 - Page 2 of 5 - Climate Impact Company

12/24/2025, 7:41 am EST

Intriguing U.S. HDD Forecasts for January 2-8

Utilizing all operational models, forecasts are agreeable to the decelerating warm pattern to near the 10-year normal for next week. In the Jan. 2-8 period, forecast models vary widely from a milder national scenario (GFS ENS/GFS) to much colder than normal (CMC ENS/ECM). The just released GFS was near the overnight consensus.

12/23/2025, 12:09 pm EST

East U.S. & Europe Turn Cold In The 6-10-day Period Increasing Risk of Natural Gas Price Rise

Natural gas prices spiked to $5.46 on December 5th anticipating a frigid East U.S. 6-10-day period. Arctic air was widespread across most of the eastern half of the U.S. The PJM System (Chicago to Washington) average temperature was a frigid 18F on December 14-15. Typical of arctic air presence when snow cover is minimal, a following warm-up is easier to generate. By December 18th the high populace PJM sector warmed above normal.

12/23/2025, 8:27 am EST

-NAO Shifting East U.S. Medium Range Forecasts Colder

The negative phase North Atlantic oscillation forecast continues and inevitably drives colder changes in the East U.S. Helping to increase East U.S. cold risk is a southern and sustained shift of snow cover across the Northeast States.

12/23/2025, 8:23 am EST

La Nina Gains Strength, Strongest Signature of Late 2025 So Far

The Nino3 SSTA is the coolest (of this episode) so far at -1.0C. The Nino34 SSTA cools to -0.8C. In the subsurface, the eastern equatorial Pacific Ocean is plenty cool to sustain La Nina. A warm Kelvin Wave shifting east near the Deadline appears to undercut the cool anomaly keeping cooler waters near the surface for trade winds to up-well to the surface.

12/22/2025, 12:43 pm EST

Latest Month 1-4 Outlook: Q1/2026 Marginally Dry/Hot in Brazil; Moderately Hot and Dry in Argentina

The Climate Impact Company month 1-4 climate outlook for South America valid for January through April is updated. The constructed analog forecast is based primarily on lingering La Nina climate through Q1/2026 coupled with unusually warm SSTA off the West Coast. A trend toward El Nino could initiate as early as April.

12/22/2025, 12:40 pm EST

Europe Surprises…Shifts MUCH Colder!

Deep upper trough forms over Eastern Europe during late December. The result is a significant cold. Arctic air gathers over Northwest Russia and some of that air mass is pulled into Europe. A vigorous storm track across the Mediterranean Sea with the northern portion all snow including Southeast Europe, The Black Sea region, and Southwest Russia.

12/21/2025, 9:26 am EST

Warm/Dry Into Early January U.S. AG Belt

The persistent “atmospheric river” storm track slamming the U.S. West Coast, particularly California, into early January leaves the Great Plains very warm and without much precipitation. The ECM dry duration forecast is up to 360 hours across parts of the Dakotas, Western Corn Belt, and southwest Great Plains wheat growing areas. Record warm temperatures are likely from Nebraska/Kansas to Texas during the warm pattern.

12/19/2025, 8:36 am EST

Warm Northeast Pacific Enhances “Atmospheric River”

The effectiveness of the “atmospheric river” storm track is enhanced by a surge in warming of the Northeast Pacific. A marine heatwave centered in the Northeast Pacific well northeast of Hawaii has strengthened and expanded to the U.S. West Coast. The warmer ocean surface temperature adds low-level atmosphere moisture entrained by the Pacific storm track and unloaded on the West U.S. with attendant latent heat release warming much of the U.S. for the next 2-3 weeks.

12/19/2025, 5:46 am EST

HDD Forecasts Still Favoring Below Average Heating Demand Through U.S. Mid-winter

The U.S. gas population weight HDD forecast for weeks 4-6 ahead continue to favor a mild climate, especially in the East. The consensus of operational models are trending colder, near the 10-year normal, for the week ending January 8th. So…operational models are pointing toward a colder regime whereas “weeklies” ignore that shift to maintain the warmth. Two AI models are cold in the 3-4-week period.

12/18/2025, 9:40 am EST

South/Southeast U.S. Drought Expansion; La Nina Climate Through Q1/2026

The NOAA/CPC Seasonal Drought Outlook is updated. The forecast indicates drought expansion for much of the South U.S. to the Mid-Atlantic region. Drought erosion or dissipation is projected for the Interior Northwest and Midwest/Mid-South U.S.

12/17/2025, 8:20 am EST

High Wind Is Precursor To The “Atmospheric River” Pattern

As a precursor to the developing “atmospheric river” pattern, widespread high wind covers the Northwest U.S. to North-central States for WED/THU. Highest wind is downslope the Northern Continental Divide into the northwest Great Plains and across mountain areas of the Northwest States. Mountain areas will observe blizzard conditions already in effect for the Washington Cascades.

12/16/2025, 8:56 am EST

When Does The Stratosphere Warm Again?

The stratospheric warming event of mid-November to mid-December is dissipating. The warming event took place on the American side of the North Pole and spawned a polar vortex in North America causing the early meteorological winter 2025-26 arctic outbreak across the eastern states. Forecast models indicate the cold stratosphere across Eurasia expands cross-polar into North America later this month.