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The National Weather Service (NWS) called for an excessive heat warning throughout the greater Seattle area through Wednesday as the region expects to suffer through 2023’s longest stretch of hot weather, but University of Washington (UW) meteorologist and professor Cliff Mass believes this is the last of the intense heat.

“Yesterday got into the mid-to-upper 80s, and much of the Western Washington area. But it’s much warmer in the Willamette Valley, and that’s very important. There is a huge difference between what’s happening here in the Puget Sound near the water, and the Willamette Valley, which is isolated from ocean-influenced temperatures,” told Jason Rantz on KTTH 770 AM. “They got to around 100 degrees. And today, in Portland, it’ll be 105. That’s pretty, pretty warm there.”

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Mass stated the jump in temperatures is typical for Willamette Valley, Portland, and other areas of Oregon, as residents of those southern areas typically face significantly higher temperatures than those in the Puget Sound region, as was the case last year.

High temperatures are expected to rise into the 90s from the Cascade foothill region for both King and Kitsap counties. Along the coast, temperatures are still expected to reach the 80s. High-temperature records in the Puget Sound area during the next few days are in the mid and upper 90s — with some single-day records vulnerable to being outdone by this current heat wave.

“One good thing is the nights are longer now than it was in June, so the lows will get down well into the 60s,” Mass said. “So it’ll cool off enough at night that cooler air will blow in, which is good. Tomorrow will be probably similar. But the good news is, by the end of the week, we’re going to transition out to much more normal conditions with temperatures in the 70s.

“And we should stay there,” Mass continued. “I suspect that this is the last major heat event for Puget Sound for the summer. The sun’s weakening now rapidly. I think this is going to be it for the real warm weather.”

For July’s unexpected increase in temperatures, Mass deduced that an anomalous circulation pattern in the atmosphere created areas of warmer-than-normal and colder-than-normal July temperatures around the nation, with particular effects over the Pacific Northwest. Mass noted that there is no suggestion in theory and observations that such a pattern was provoked by global warming — just as there is little to no global warming influence on the Puget Sound’s most current heat wave.

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“Climate change, or global warming as I like to call it, that’s contributing a little bit,” Mass told Rantz on KTTH 770 AM. “We’ve warmed up about two degrees Fahrenheit over the last 50 years. So if you have a heatwave, one or two degrees of that could be the cause of it. But when you’re at 85 degrees or 90, you know that two degrees is a relatively small portion of the heatwave. So most of our heat waves are still natural here.”

In addition to the current heat spike, smoke from the lightning-initiated Sourdough fire in the North Cascades is causing further issues with air quality. The air quality index (AQI) reached a “moderate” ranking of 57 when smoke descended onto Western Washington Sunday evening.

“The sourdough fire into the North Cascades is in pretty inaccessible territory,” Mass said. “That’s why they haven’t been able to put it out very rapidly.”

Listen to the Jason Rantz Show weekday afternoons from 3 – 7 p.m. on KTTH 770 AM (or HD Radio 97.3 FM HD-Channel 3). Subscribe to the podcast here.