Temperatures could soar to highest levels of 2023 in Seattle, Portland

A building heat wave will usher in some of the hottest weather of the year to date. The extended hot spell combined with other factors will raise the wildfire risk across the Northwest.

An unusually wet pattern across much of the interior Northwest in early August has limited temperatures and the risk of wildfires, but a drastic shift in the weather pattern is about to bring the heat, AccuWeather forecasters say.

The incoming heat will not be limited to the interior Northwest, as places like Seattle and Portland could be challenging records next week with temperatures approaching the highest level so far this summer.

Monsoon moisture to suppress heat through the weekend

An active setup is currently in place across the Southwest, with former Tropical Storm Eugene combining with monsoon moisture to promote showers and thunderstorms across the region, especially in the higher elevations.

These two factors will displace the heat dome that has been parked over the Southwest throughout most of the summer. As the heat dome shifts north, it will cause temperatures to rise throughout the weekend, providing a preview of an even hotter weather pattern predicted to unfold next week.

An extended stretch of heat to unfold in the Pacific Northwest

Temperatures will begin to swell this weekend, with the potential for a heat wave to begin early in the week and last several days along the Interstate 5 corridor from Seattle through Sacramento.

In Seattle, temperatures are forecast to approach or exceed the 90-degree mark on Monday and Tuesday. High temperatures will be a few degrees shy of daily records but significantly higher than the historical average, which is in the upper 70s in mid-August. The highest temperature recorded in Seattle so far this year was 91 degrees, which was measured multiple times in July.

A similar scenario is expected in Portland, where temperatures will flirt with the 100-degree mark, about 5-15 degrees above the historical average, over a multiday stretch.

Heat of this magnitude could end up challenging daily and monthly record-high temperatures in towns along the I-5 corridor, including Medford, Oregon. The mercury in Medford could approach 110 degrees on Monday, just a few ticks below the August record of 114 degrees, set on Aug. 8, 1981.

Forecasters urge people across the region to take extra precautions, including drinking plenty of water and wearing sunscreen, when spending extended periods of time outdoors in the heat.

In addition to the potential record heat, the risk of wildfire activity will also increase.

Wildfire threat to expand

The extended hot spell will undoubtedly dry out fuels across the Northwest this weekend and next week, raising the wildfire danger.

While a few fires have already occurred in the Northwest this year, the number of acres burned across the nation as a whole is well below the historical average. As of Thursday, just over 1,400,000 acres have burned across the United States, which is the lowest number of acres burned in the last 10 years to date.

AccuWeather meteorologists will be closely monitoring any fire activity across the Northwest next week, as the risk can become high as a result of the heat, locally gusty winds and lightning strikes from thunderstorms associated with the monsoon.

AccuWeather long-range forecasters are predicting a high risk of wildfires across large areas of Washington, Oregon and Idaho into autumn.

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