Blazing heat to return to Pacific Northwest after refreshing weekend

By Kyle Elliott, AccuWeather meteorologist

By Faith Eherts, AccuWeather meteorologist

August 12, 2018, 12:21:43 PM EDT

A welcome break from the extreme heat that has been scorching the Pacific Northwest is in store through Sunday, but the heat relief will not last for long.

High temperatures in Seattle and Portland, Oregon, have averaged 10-15 degrees Fahrenheit above normal this past week. The mercury soared into the 90s for the sixth consecutive day in Portland on Friday, and Seattle carded three consecutive 90-degree days spanning Tuesday to Thursday.

The streak of 90-degree days ended in Seattle on Friday and in Portland on Saturday as a dip in the jet stream temporarily squashes the expansive heat dome through the weekend. 

“Cool air, and even some clouds, will move farther inland through Sunday, bringing comfortable high temperatures in the 70s grace for the Interstate 5 corridor from Seattle to Portland,” AccuWeather Meteorologist Ryan Adamson said.

However, the cooler air and scattered shower or two will do little to extinguish the fire threat across the region.

Nearly 20 active fires that have charred over 210,000 acres are burning in Washington and Oregon alone as of Friday. Currently, there are about 80 active blazes present across the western United States.

"While there will be a significant cooldown for the region into Sunday, there will also be an increase in winds," AccuWeather Meteorologist Evan Duffey warned.

This could create a volatile period of rapidly spreading wildfires this weekend.

Duffey stressed that the uncertainty in wind direction will add unpredictability in the direction that wildfires may spread.

"This creates a dangerous situation for wildland firefighters in the region," he added.

Anyone living or traveling through the western half of North America should remain up to date on local watches, warnings and alerts and be prepared to evacuate at a moment's notice.

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Hikers and tourists spending time outdoors should have a plan of action in place in the event that mandatory evacuation orders are issued.

Download the free AccuWeather app to check on the latest coverage of beneficial showers or direction of troublesome winds.

Although winds should lessen again by Monday, the massive heat dome confined to the Southwest this weekend will once again bulge back northward and bring more heat back to the Northwest.

“While temperatures in Montana and the western Dakotas will fall into the 80s and lower 90s F early next week, Washington and Oregon will begin to heat back up,” Adamson warned.

While high temperatures should not be quite as high as what they were this past week, areas from Portland to interior parts of Washington and Oregon could once again experience 90-degree heat, with mid- to upper 80s returning to Seattle.

Anybody with respiratory problems, the elderly, young children and those that mind the heat should be sure to drink plenty of fluids and limit time outdoors during the hottest parts of the day to reduce the risk for heat-related illness.

Unfortunately, no meaningful change in the weather pattern is in sight for at least the next couple of weeks. The hottest and driest weather, relative to normal, is expected to remain across the western U.S.

Thus, firefighters already dealing with an above-average fire season should expect little, if any, aid from Mother Nature in the weeks to come as the acreage burned continues to increase.