Monday started wet in parts of northwest Oregon and western Washington, and things were only expected to get wetter.
A strong atmospheric river is expected to bring inches of rain to the area between Monday and Wednesday and much of the region is under a flood watch.
An atmospheric river is essentially band of water vapor moving through the sky.
Unlike some atmospheric rivers earlier this fall, December’s event is expected to lead to some flooding, as it comes after several days of rain.
A map from the National Weather Service shows which parts of the region could see four or more inches of rain over the next several days.
The 72-hour probability to exceed 4 inches of rainfall through Thursday, Dec. 11, 2025, in Oregon and Washington.Courtesy of NOAA
Some areas could see even more rain. Another map from the National Weather Service shows that in the coast range near Tillamook, there’s a 74% chance of six or more inches of rain between 4 a.m. Monday and 4 a.m. Thursday.
The 72-hour probability to exceed 6 inches of rainfall through Thursday, Dec. 11, 2025, in Oregon and Washington.Courtesy of NOAA
“The heaviest rain is expected to fall north of Lane County,” the National Weather Service said in a release. “Widespread river, small stream, and urban flooding is likely to occur. People, structures, and roads located below steep slopes, in canyons, and near the mouths of canyons may be at serious risk from rapidly moving landslides or debris flows.”
“Those living in areas prone to flooding should be prepared to take action should flooding develop,” the agency said.
