Heat to build, exacerbate wildfire danger in northwestern US into midweek

As near-record heat ramps up in the northwestern United States into midweek, wildfire and poor air quality concerns will also mount.

“Temperatures will be on the rise early this week across the northwestern U.S. as high pressure builds to the north,” AccuWeather Meteorologist and western U.S. blogger Jordan Root said.

The core of the heat is expected to take hold of the Interstate-5 corridor from Eugene and Portland, Oregon, to Olympia and Seattle, Washington.

"Seattle and Portland both could challenge record highs," Root said.

Tuesday and Wednesday are expected to be the hottest days, with highs near or above 90 F in these cities.

The sizzling conditions can further strain the many residents who live in non-air conditioned dwellings and have been taxed by an unseasonably warm August thus far.

Temperatures have averaged 3-4 degrees Fahrenheit above normal along the I-5 corridor since the start of the month.

Partaking in strenuous outdoor activities during the early morning and evening hours can limit the risk of heat-related illnesses. Anyone who spends time outdoors should be sure to drink plenty of water and wear light-colored and loose-fitted clothing.

Never leave pets or children in a locked vehicle, even if the windows are partially opened. Temperatures inside can turn lethal in a matter of minutes.

The heat will not be the only hazard that residents and visitors should be mindful of.

"Winds will shift to the north-northeast on Tuesday which will bring a lot of smoke from wildfires in British Columbia into the Northwest," Root said.

Scenes similar to what occurred last week with smoke shrouding the skyline’s of Seattle and Portland may again play out this week.

On Monday, there were numerous flight delays at Sea-Tac International Airport due to poor visibility from the haze and thick smoke. Flight delays will be likely in the I-5 corridor and surrounding areas through midweek.

Root said that if the smoke becomes thick enough, it could hinder how warm it gets during the afternoon and evening hours in some locations.

Regardless, the combination of the warmth and poor air quality will make it necessary for people to take precautions.

While children, the elderly and those with pre-existing respiratory problems will be at greatest risk of suffering ill effects from the smoke, everyone spending any length of time outdoors should use caution.

The risk of new wildfire ignition will remain high in this pattern.

Outside of wet weather spreading into the northern Rockies early this week, much of the region will stay rain-free.

Spotty thunderstorms may ignite in the Washington and Oregon Cascades and Blue Mountains, but they may do more harm than good by generating frequent lightning, gusty winds and little to no rainfall.

Root expects the wind to turn more westerly during the second half of the week, which will help to disperse some of the smoke and bring in cooler air from the Pacific Ocean.

Residents and local officials should be mindful that the wildfire danger may only further increase heading into the first part of fall despite average temperatures declining.

“Episodes of wind traditionally increase during September and October,” AccuWeather Senior Meteorologist Alex Sosnowski said.

“Even when temperatures are relatively low, gusty winds can still cause a fire to rapidly spread when the air and brush are dry,” he added.

Multiple soaking rainstorms are necessary to relieve the wildfire danger, but such storms typically do not become more frequent along the West Coast until November and December.

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