Oregon starts this December Sunday under steady rain and wind across the Portland metro, signaling the arrival of a long-duration storm system now feeding Pacific moisture into the region. Streets are already slick, and low clouds hang over bridges as drivers navigate standing water near I-5 and I-84.
According to the National Weather Service in Portland, a Flood Watch remains in effect from late Sunday night through Thursday, with localized Flood Warnings issued for parts of Johnson Creek, Tillamook County, and Wahkiakum County, WA. Forecasters say an atmospheric river will keep the region soaked, producing 2 to 4 inches of rain across western valleys and significantly higher totals in the Coast Range and Cascades.
Flooding from excessive runoff is possible in creeks, streams, and urban low spots. Minor flooding is already occurring along Johnson Creek, where water levels could rise another 1.5 feet by Tuesday. The Grays and Wilson Rivers are also nearing flood stage, with the heaviest rain expected between Monday morning and Wednesday afternoon.
Winds gusting near 35 mph may accompany the heaviest showers, and saturated soils increase the risk of landslides and debris flows—particularly near burn scars and canyon slopes. Drivers should avoid water-covered roads and never attempt to cross barricades.
After Thursday, rainfall should taper, but rivers may remain elevated into Friday. Temperatures will stay mild, with highs in the upper 50s and lows in the upper 40s, maintaining wet, unstable conditions across the metro.
Five-Day Outlook (Sun–Thu):
• Today: Rain, high 56°.
• Monday: Rain, breezy, high 57°.
• Tuesday: Heavy rain, high 56°.
• Wednesday: Rain continues, high 57°.
• Thursday: Scattered showers, high 54°.
