After Two Wet Winters In A Row, Can Eaton Canyon Get Lucky Again?

Over the past 2 years, MyEatonCanyon.com has been monitoring changes to Eaton Canyon following the drenching winter 2023 rains, publishing articles on rain totals, tree sapling growth, and creek flow. Eaton Canyon has an exceedingly rare semi-arid Mediterranean climate type, in that not only do we have a winter wet season and summer dry season that is atypical throughout planet Earth, but our wet and dry seasons are far more pronounced than traditional Mediterranean climates. This fact puts Eaton Canyons’ ecology in an awkward position where it must be able to handle both several feet of rainfall in some years and 8+ month stretches without a single drop.

As we head into late autumn in Southern California, attention turns towards the equatorial East Pacific around and west of the Galapagos Islands. This particular part of the Pacific ocean undergoes periodic and regular sea surface temperature changes that impact the global weather in a phenomena we call the “El Nino Southern Oscillation” or “ENSO” for short. When ocean temperatures in this area are warmer than average, we call it El Nino. When they are cooler than average, we call this La Niña. These two episodes can last anywhere between 6 months and 3 years. La Niña conditions typically result in drier than average winters in California, though this is a generalization, not a rule. Famously wet years in the Golden State such as 2023 were La Niña years.

La Niña years more often than not generate persistent atmospheric ridging over or just west of California during the winter months, deflecting incoming Pacific rainstorms north into British Columbia. Meanwhile, El Nino years more often than not feature a strong subtropical jet stream that connects moisture between Hawai’i and the Southern California coast and can easily cut through those same ridges.

 

As of October 2024, the National Oceanic and Atmospheric Administration has a “La Niña Watch” in effect with cooler than average water temperatures in the equatorial east Pacific expected this winter. Earlier forecasts issued this past summer by NOAA called for more robust La Niña than we are currently seeing, and we’ve instead been hovering around neutral ENSO conditions. While conditions are still within the forecast envelope from last autumn, reality has been on the warm side.

 

Indeed, forecast models have begun calling for below average winter rainfall across the entire state, including Eaton Canyon. While these forecasts could very well be wrong, especially on a local level, optimism is not high for a wet winter 2025.