As a persistent La Niña pattern settles in for the 2025-2026 winter, understanding its complex influence on the jet stream and regional weather is crucial for anticipating temperature, precipitation, and severe weather across the United States from late fall through early spring.
A new La Niña event has officially commenced, setting the stage for potentially significant shifts in weather patterns across the United States as we transition from late fall into the 2025-2026 winter. Declared by the National Oceanic and Atmospheric Administration (NOAA), this phenomenon, characterized by cooler-than-average sea surface temperatures in the equatorial Pacific, holds wide-reaching implications for temperature, precipitation, and even severe weather nationwide, as detailed by NOAA and the National Weather Service (NWS).
Understanding La Niña: The Climate Driver
La Niña is the “cool sister” to El Niño, forming part of the broader El Niño-Southern Oscillation (ENSO) climate pattern. It emerges when stronger-than-normal easterly trade winds push warm surface waters westward toward Indonesia, allowing colder water from the ocean depths to rise to the surface near South America. This ocean-atmosphere pattern influences the position of high and low pressure areas globally, thereby steering the jet stream and guiding storm tracks across the United States. Since it first emerged in September, water temperature anomalies in critical parts of the central and eastern Pacific have dropped below the -0.5 degrees Celsius threshold, confirming the pattern’s re-establishment, according to NOAA.
While this current event is forecast to be a weak La Niña, with water temperature anomalies expected to remain in the -0.5°C to -1.0°C range, its influence is still substantial. Historically, stronger La Niñas tend to bring widespread warmth, while moderate events lean cooler. A weak event, however, can often result in a mixed bag of outcomes, making the winter highly variable and susceptible to other atmospheric influences, notes forecasters at The Weather Company and Atmospheric G2.
Temperature Outlook: A Tale of Two Regions
The 2025-2026 winter outlook paints a contrasting picture for temperatures across the U.S., largely driven by the prevailing La Niña pattern. The latest November temperature outlook indicates a continuation of warmth for many areas, at least early in the season.
- Northern States: Regions from the Pacific Northwest through the Upper Midwest and into the Great Lakes are generally forecast to experience colder-than-average temperatures. This means a higher likelihood of frequent arctic air intrusions and more snowy days for cities like Minneapolis, Fargo, Seattle, and Portland.
- Southern States: Conversely, the southern tier of states, from central and southern California through St. Louis to the Carolinas, typically sees warmer-than-normal conditions with fewer prolonged cold snaps. Residents in Dallas, Tallahassee, and Fayetteville might enjoy more mild winter days. Florida, however, could see cooler-than-average temperatures in November due to enhanced rainfall and cloud cover.
- Northeast and Mid-Atlantic: For this region, a weak La Niña can be highly unpredictable. The jet stream’s storm track might sometimes be too far north for major snow, while at other times, a well-timed cold outbreak could trigger significant snowstorms.
As December arrives, the shift becomes more pronounced in the Northern Plains and Pacific Northwest, with cold blasts becoming longer-lived.
By January, the eastern U.S. might experience brief milder interludes, even as the Pacific Northwest continues its trend of cooler weather, as shown in the January 2026 outlook by The Weather Company and Atmospheric G2.
Precipitation Patterns: Drought Concerns and Snow Opportunities
La Niña often flips the precipitation map across the United States, bringing increased moisture to some areas and heightened drought risks to others. The forecast for November through January highlights these divergent patterns.
- Wetter North: The Pacific Northwest and Northern Rockies frequently bear the brunt of winter storms, resulting in heavy rain, high mountain snows, and a thicker snowpack. This is good news for skiers and water supplies. The Ohio Valley, Great Lakes, and Northern Plains can also expect a snowier-than-average winter due to frequent Alberta clippers and lake-effect snow events. Drought relief is likely for portions of the Great Lakes and Midwest.
- Drier South: Conditions tend to be drier than normal across California and the Southwest, raising concerns for wildfires and water shortages. Similarly, the Gulf Coast and Southeast often see fewer winter storms and soaking rains as the storm track typically stays north, increasing the chances of winter brush fires and hindering drought improvement. North Carolina, for example, typically experiences warmer and drier conditions during La Niña winters, although past events have shown considerable variability.
La Niña and Severe Weather: An Exception for Florida
Research from NOAA’s Storm Prediction Center indicates that severe weather outbreaks are generally more likely across the U.S. during La Niña events. This is often attributed to atmospheric dynamics that become more favorable for tornadoes, hail, and damaging winds. However, Florida stands out as a notable exception to this rule.
During significant La Niña events, Florida and the Gulf Coast tend to experience a substantial drop in severe weather reports. This is primarily because the jet stream, which provides the necessary dynamics for severe weather outbreaks, is often displaced well to the north of the Sunshine State. In contrast, the El Niño phase of ENSO tends to create more favorable conditions for tornado outbreaks, as tragically demonstrated by a historic event in February 1998 that claimed 42 lives across central Florida.
The Complexity of Other Atmospheric Influences
While La Niña provides a general framework for winter weather, especially a weak one, other ocean-atmospheric interactions, known as “teleconnections,” can significantly modify its impacts. These patterns can bring their own localized weather characteristics for days or weeks, contributing to the overall variability of the winter season:
- Arctic Oscillation (AO) and North Atlantic Oscillation (NAO): These measure pressure differences that determine how easily cold air can push south from the Arctic. A ‘negative’ phase can create blocking patterns, forcing arctic outbreaks southward, leading to more cold and snow in the Great Lakes and Northeast.
- Quasi-Biennial Oscillation (QBO): This measures stratospheric wind speeds, indicating the strength of the polar vortex. A weak polar vortex allows chunks of arctic air to spill much farther south into the U.S.
- Madden-Julian Oscillation (MJO): This pulse of tropical thunderstorms can influence where storms form in the southern U.S. and drive cold shots toward the East Coast.
- Pacific Decadal Oscillation (PDO): A long-term temperature pattern in the North Pacific, a negative PDO phase can reinforce typical La Niña weather patterns, intensifying cool, wet conditions in the Pacific Northwest and cold, snowy weather in the Great Lakes, while keeping the South mild and dry. The PDO is currently in a negative phase.
Historical Context and Long-Term Implications
The 2025-2026 winter marks a new La Niña event, distinct from the rare “triple-dip” La Niña that persisted from the 2020-21 through the 2022-23 winters. While the previous triple-dip saw varying impacts, including a very wet winter in North Carolina in 2020-21 contrasting with a warmer and drier 2021-22, historical triple-dips (like 1974-76 and 1999-2001) demonstrated pronounced effects, particularly on precipitation and drought.
The last triple-dip La Niña, from 1999 to 2001, for instance, led to severe drought across North Carolina, with some areas experiencing more than a year’s worth of rainfall deficits. While current drought deficits are not as extreme across the state, drought conditions remain a concern, particularly after recent dry periods. For the 2025-2026 winter, the drier-than-normal conditions expected in the Southern tier will likely extend the drought that has developed this fall, impacting water levels in lakes and rivers, according to The Weather Company and Atmospheric G2.
Despite the overall warmer and drier lean of La Niña winters in the South, snow is never entirely ruled out. As previous winters have shown, “windows of opportunity” can still open, delivering sizable snow events even amidst a generally warm and dry season. This variability underscores the dynamic nature of winter weather under La Niña’s influence, reminding us that constant monitoring of atmospheric patterns remains crucial.
