North Fork Stillaguamish River near Arlington

1. 15.00 ftthe North Fork Stillaguamish River will cause extensive flooding from near Darrington downstream to the confluence with the South Fork Stillaguamish River...including Oso...Cicero...Swede Heaven and SR 530. Flood waters will also cause riverbank erosion. Flooding will occur all along the river including headwaters...tributaries...and other streams within and near the N Fork Stillaguamish River Basin. A stage of 15 feet corresponds to Phase 4 in the Snohomish County Flood Warning System.
2. 14.00 ftthe North Fork Stillaguamish River will cause flooding in the Cicero and Swede Heaven areas...Oso Loop Road...and SR 530. Flood waters will also cause riverbank erosion. A stage of 14 feet corresponds to Phase 3 in the Snohomish County Flood Warning System.
3. 13.00 ftthe North Fork Stillaguamish River will cause flooding of Oso Loop Road and cause minor riverbank erosion. A stage of 13 feet corresponds to Phase 2 in the Snohomish County Flood Warning System.

Chance of flooding, September to November

The three-month chances are the River Forecast Centers’ long-range flood outlook, issued September 25, 2026.

Most recent crests

• December 5, 2023: 15.21 ft
• December 5, 2023: 15.21 ft
• November 5, 2022: 13.09 ft
• February 1, 2020: 14.57 ft
• January 7, 2020: 13.38 ft
• November 22, 2017: 14.51 ft
• November 17, 2015: 15.07 ft
• November 13, 2015: 14.79 ft
• January 5, 2015: 12.90 ft
• November 26, 2014: 12.90 ft

• DownstreamStillaguamish River at Arlington
• Oso
• Stillaguamish River at I-5
• Stillaguamish River
• South Fork Stillaguamish River at Granite Falls
• South Fork Stillaguamish River at Jordan Rd. Bridge
• Stillaguamish River at Stanwood
• South Fork Stillaguamish River at Verlot

Forecasts by the Northwest River Forecast Center. Forecasts are issued routinely year-round. River forecasts for this location take into account past and future precipitation. The stages/flows that will occur may be different if future rainfall is different than forecast.

Stage, flood stages, impacts and crest history from NOAA’s National Water Prediction Service. Streamflow and the daily record from the U.S. Geological Survey.