Portland, Oregon – Oregon is facing an extended stretch of hazardous weather conditions as a series of powerful Pacific storms is expected to impact the state from December 20 through early January, according to the latest outlook from the NOAA Climate Prediction Center. Forecasters warn that repeated rounds of heavy rain, strong winds, and mountain snowfall could significantly raise the risk of flooding and landslides across large portions of the state.
Meteorologists say multiple atmospheric rivers are forecast to begin pushing into the Pacific Northwest around December 20, directing deep Pacific moisture into western Oregon. With soils already saturated following recent storms in Washington and northern Oregon, conditions are favorable for runoff and rapid water accumulation as the storm pattern intensifies.
Prolonged Atmospheric River Pattern Developing
NOAA forecasters explain that the upcoming pattern is being driven by a persistent storm track across the Pacific Ocean, enhanced by La Niña conditions. These systems are expected to arrive in waves rather than as a single storm, creating a prolonged period of unsettled weather.
A moderate risk (40–60%) of heavy precipitation has been issued for much of western Oregon from December 20 through December 26, stretching from coastal counties through the Willamette Valley and eastward to the Cascade foothills. Rainfall totals could build steadily with each passing system, increasing pressure on rivers, streams, and drainage infrastructure.
Flooding Concerns Increase Across Western Oregon
Forecasters caution that flooding concerns are likely to expand southward into Oregon by mid-next week. Areas most vulnerable include low-lying urban locations, flood-prone river basins, and communities near smaller creeks that can rise quickly during sustained rainfall.
Hydrologists emphasize that even moderate rainfall amounts could lead to problems because the ground has limited capacity to absorb additional moisture. As rainfall continues, runoff is expected to increase, raising the risk of roadway flooding, overwhelmed storm drains, and river levels approaching or exceeding bankfull in some locations.
Landslide Risk Elevated in Steep Terrain
Repeated rainfall over saturated soils also raises the likelihood of landslides and debris flows, particularly in western and southwestern Oregon. Forecasters note that areas with steep slopes, burn scars, and unstable soils are especially vulnerable during prolonged wet periods.
Transportation corridors along hillsides and mountain passes may face closures if slides occur, while rural communities near slopes could experience localized impacts. Emergency managers urge residents in landslide-prone areas to remain alert for signs such as ground cracking, tilting trees, or sudden changes in drainage patterns.
Heavy Snow and Hazardous Travel in the Cascades
In addition to rain at lower elevations, NOAA highlights a moderate risk of heavy snow for the Cascade Range during the December 20–26 period. Snowfall could be significant at higher elevations, creating dangerous travel conditions over mountain passes.
Snow combined with gusty winds may lead to reduced visibility, drifting, and difficult driving conditions, particularly during peak storm periods. Officials advise travelers to carry winter supplies and monitor pass conditions closely if holiday travel plans include mountain routes.
Strong Winds Expected Along Coast and Valleys
Enhanced onshore flow associated with these storms is also expected to bring periods of strong winds along the Oregon coast, interior valleys, and higher elevations. Wind gusts could become hazardous at times, especially during the strongest moisture surges embedded within the atmospheric rivers.
These winds may lead to downed trees, scattered power outages, and difficult conditions for high-profile vehicles. Coastal areas may experience rough seas and hazardous marine conditions during the most intense systems.
Wet Pattern Likely to Persist Into Early January
Looking beyond Christmas, NOAA indicates that above-normal precipitation chances extend into early January, with the active storm track expected to remain in place through at least the first full week of 2026. This means flooding and landslide risks could remain elevated even after the initial storms pass.
Forecasters stress that impacts will depend on how storms overlap and how quickly rivers and soils can recover between systems.
What Residents Should Do
Residents across Oregon are encouraged to closely monitor local National Weather Service forecasts for flood watches, wind advisories, and winter storm warnings as conditions evolve. Preparing drainage areas, avoiding flooded roads, and staying informed can help reduce risk during this prolonged wet period.
As the storm pattern unfolds, officials urge the public to take alerts seriously and adjust travel and outdoor plans accordingly. Share your experiences in the comments below.