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Cool and cloudy skies ahead with air quality to improve after fireworks

There’s a joke in Seattle that summer doesn’t start around here until July 12– three weeks after the solstice and nearly a week after Independence Day.

“And I have a feeling that may be true this year,” says KNKX weather expert Cliff Mass after a damp Fourth of July with cloudy skies and cool temperatures around 70 degrees.


“This is not a warmer-than-normal period. But it’s actually quite typical, if you look back at the last several decades,” Mass said.

The damp and wet trend will continue this week, with lots more clouds and sprinkles in the forecast as British Columbia gets hit with a major weather system that is expected to dump several inches of rain there and send some marginal precipitation our way.

“I’m afraid that over the weekend this trough of low pressure that’s been hanging around for so long isn’t going away,” Mass said.

And he says the air quality around the region once again rapidly declined as people shot off fireworks in honor of the Fourth of July.


“A lot of places in western Washington had air quality that was some of the worst on the planet,” he said. “Worse than Beijing and India.  The particulates in the atmosphere just skyrocketed.”

You can see the effects recorded in data kept online by the Puget Sound Clean Air Agency.

“We’re putting a lot of particulates in the air, small particles, and even some toxic elements, like heavy metals—both due to private shows and due to the public shows,” Mass said, adding that those numbers drop almost as sharply as they go up once people stop setting off the fireworks.

“They’re starting to improve now, I think as we get into the next day, the air quality will return to normal,” he said.


Mass says there might be some lighter skies Saturday afternoon. Monday looks like the best day of the week ahead. Then Tuesday and Wednesday will be very wet over much of western Washington.

He says this July is shaping up to go down as one of the wetter ones in recent memory.

“We had some rain already in July: 0.34 inches (in Seattle). So we’re already, here in Seattle, the wettest July since 2016,” Mass said, adding that we will get more.

“So, I think it’s a very good chance we’re going to end up with a quite a wet July,” he said. “In fact, it could be one of the wettest Julys on record before all this is over.”


But Mass says air quality from wildfire smoke won’t likely be an issue at this point, at least for the next several weeks. Right now, there are no fires burning in the Northwest, so there is no local smoke.

A recent surge of smoke from wildfires in Alaska moved into the upper atmosphere over the northwest last week and could be seen in satellite pictures. It’s mostly gone now.

Mass expects the several inches of rain coming into British Columbia and Alberta to over the next several days to keep many wildfires from materializing there.

“And that is really going to put any potential for major fires to sleep for at least several weeks, probably a month,” Mass said.  

Weather with Cliff Mass airs at 9:02 a.m. Friday, right after BirdNote, and twice on Friday afternoons during All Things Considered. The feature is hosted by KNKX environment reporter Bellamy Pailthorp. Cliff Mass is a University of Washington professor of atmospheric sciences, a renowned Seattle weather prognosticator, anda popular weather blogger. You can also subscribe to podcasts of Weather with Cliff Mass shows, viaiTunes or Google Play.

Bellamy Pailthorp covers the environment for KNKX with an emphasis on climate justice, human health and food sovereignty. She enjoys reporting about how we will power our future while maintaining healthy cultures and livable cities. Story tips can be sent to