SEATTLE – The hum of steady rain and the flash of headlights on wet pavement mark the start of a volatile Halloween weekend across western Washington. Rivers are swelling, mountain passes are slick, and the air carries that dense, earthy scent only a Pacific storm can bring.
A Hydrologic Outlook from the National Weather Service in Seattle warns of heavy rainfall through Sunday morning, with localized flooding possible from Mason County north through King, Snohomish, and Skagit counties. A strong atmospheric river will push into the region Friday, delivering two to six inches of rain across the Olympic Peninsula and northern Cascades. The heaviest rainfall is expected along the windward slopes of the Olympics and central Cascade foothills, where saturated soils could trigger debris flows or flash flooding.
Forecasters say the Skokomish River could reach minor flood stage by late Saturday, with other rivers — including the Snoqualmie, Skykomish, and Bogachiel — nearing bankfull levels by Sunday. Urban areas could also experience nuisance flooding where leaves clog storm drains.
Drivers along I-5, Highway 2, and US-101 should prepare for ponding water, reduced visibility, and hydroplaning risks, especially during peak rainfall periods late Friday and Saturday. Winds may gust above 25 mph near Puget Sound, complicating travel for high-profile vehicles.
Conditions will improve by late Sunday as the atmospheric river weakens, though lingering showers and high streamflows will persist into early next week. Residents should secure outdoor items, check local river gauges, and avoid flooded roads — it only takes a few inches of water to stall a vehicle.
Five-Day Forecast for Seattle, WA:
Fri: 56/51 – Rain develops; heavy at times late.
Sat: 60/46 – Steady rain; flooding risk in low areas.
Sun: 55/45 – Showers taper; partly sunny late.
Mon: 54/47 – Cloudy; scattered rain returns.
Tue: 57/50 – Breezy; more rain possible north of city.
