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PNW holiday travel forecast: What to expect on I-5 and I-84

File photo of white-out conditions that hit the Gorge along I-84 on January 3, 2022 (Courtesy: ODOT).

PORTLAND, Ore. (KOIN) — Drivers leaving Portland for the holidays can expect varying weather conditions based on the direction they’re headed this week, as a severe winter storm bears down on the greater Portland area Thursday.

Here’s what travelers should plan for:

Portland to Seattle

Freezing temperatures are in Thursday’s forecast for all areas along Interstate 5 between Portland and Seattle. A high of 24 degrees is expected along I-5 from Portland to the Canadian border, while easterly 17- to 24-mph winds will lend to freezing rain and icy road conditions in Portland and throughout the Willamette Valley on Thursday and Friday. Meanwhile, milder 5- to 8-mph winds will be possible in the Seattle area.

Regional temperatures on Thursday. (NWS)

The National Weather Service has issued a winter storm watch for all of Northwestern Oregon and the Southwestern corner of Washington from Thursday to Friday morning. Starting Thursday night and persisting into Christmas Day, there is a strong chance of various forms of precipitation falling along I-5 between Portland and Seattle, including rain, freezing rain, snow and sleet.

Temperatures are predicted to heat up into the mid 30s and low 40s on Friday. Freezing rain will remain possible in the Portland area between Thursday night and Friday. In the Seattle area, a wintery mix of snow and rain will subside into rain by Friday night. Rainy weather will persist in Portland and Seattle through the weekend.

Portland to Boise

Weather conditions along I-84 are forecast to be especially treacherous through the Columbia River Gorge and into the Hood River Valley between Wednesday night and Saturday afternoon. Freezing rain, subzero wind-chill temperatures and freezing mist whipped up from the Columbia River by 20- to 70-mph winds are expected to make regional stretches of I-84 especially hazardous.

The National Weather Service has issued a variety of weather advisories for areas along I-84 between Portland and Boise this week. A winter storm watch will be in effect on Thursday and Friday between Portland and Hood River. As much as half an inch of ice could impact highway traffic between Portland and Corbett during this time. Approximately 2 to 4 inches of snow will also be possible from Cascade Locks to Hood River.

“Power outages and tree damage are possible due to the ice,” the NWS said. “Travel could be difficult. The hazardous conditions could impact the Thursday afternoon commute and the Friday morning commute. Wind chills dropping as low as 15 below zero could cause frostbite on exposed skin.”

Farther east, a wind chill advisory will remain in effect between Hood River and Hermiston from 10 p.m. Wednesday to 10 a.m. Friday, when extremely cold wind chills will be possible along this region of I-84. Wind chill temperatures could drop to as low as 20 degrees below zero.

“This is a very complex system and Holiday travelers are urged to be prepared for rapidly changing conditions and winter driving,” the NWS said. “Slow down and take caution, allowing for slowed travel times, slick conditions, and poor traffic conditions. Key an eye out for updates to the forecast leading into this event.”

Continuing on I-84, more winter weather is forecast between Pendleton and Boise. One to three inches of snow will be possible in this area on Thursday. Single-digit lows will be possible from La Grande to Boise on Wednesday night. A mix of freezing rain and snow will be possible between Friday and Saturday in La Grande. Freezing rain will also be possible in Boise on Saturday. Temperatures are forecast to rise into the high 30s by Saturday, followed by cloudy and slightly rainy weather into next week.

Cold arctic air will drop temperatures into the teens on Thursday. (KOIN)

Portland to Medford

A winter storm watch will be in place for the entire Willamette Valley from Thursday to Friday Afternoon. I-5 drivers could face a tenth of an inch to half an inch of ice between Portland and Eugene during this time. 

Temperatures will grow significantly warmer as I-5 drivers head farther south. While Portland will see a high of 20 degrees on Thursday, Eugene is forecast for a high of 35. Medford, meanwhile, is expected to see a considerably mild 47-degree day.

Rain is likely in Medford on Thursday and chances of rain will persist into next week. Christmas Day in Medford is expected to be cloudy and mostly dry with a high of 58 degrees.