While the official declaration of a La Niña event is still pending, the Pacific Northwest (PNW) has already experienced a remarkable early season snowfall, surprising many weather enthusiasts and winter sports lovers alike.

Despite the current neutral phase of the El Niño-Southern Oscillation (ENSO), the region has seen significant snow accumulation at many ski resorts, with some opening their doors before or around Thanksgiving. This unexpected early season snowfall highlights the significant role of meteorological variability in shaping weather patterns, even in the absence of a strong ENSO signal.

While La Niña conditions are often associated with colder, wetter winters in the PNW, the current neutral phase has provided a favorable setup for early season snowfall. This is likely due to a combination of factors, including specific atmospheric patterns and localized weather events.

The Climate Prediction Center (CPC) has issued a La Niña Watch, indicating a 59% chance of La Niña developing between November and January 2025. If La Niña does materialize, it is expected to be weak and short-lived, with the potential to influence weather patterns from January through March.

A Look Back: Snowfall in Recent Years

Comparing the current snowfall to previous years, it's evident that variability plays a significant role in winter weather patterns. While 2020-2022 were La Niña years, the snowfall patterns varied significantly. The current neutral year, 2024, has already surpassed the snowfall of some La Niña years, emphasizing the unpredictable nature of winter weather.

Temperature Outlook

The three-month temperature outlook from the CPC suggests a 30-50% chance of below-normal temperatures for the PNW from December 2024 to February 2025. Additionally, there is a 33-40% chance of above-normal precipitation during this period. 1    

While the early season snowfall has been impressive, it's important to note that weather patterns can change rapidly. As the winter progresses, it will be crucial to monitor the development of La Niña and other weather systems to assess the potential for continued snowfall and winter weather conditions in the PNW.