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Heat Wave Hitting Western Washington This Weekend Will Drive Temps Into High 60s

Tim Durkan
Tim Durkan Photography
A recent sunset at Alki Beach in West Seattle

Time to get out the short sleeves and sunscreen. Warm winds from the south and east are going to push the mercury to nearly summer-like levels in western Washington this weekend, says KNKX weather expert Cliff Mass.

“By the time we get to Sunday and Monday, you will not believe it, with temperatures getting up into the mid-60s – even higher in some locations,” said Mass, a professor of Atmospheric Sciences at the University of Washington in Seattle.

Normal Friday

Mass says Friday will be relatively cool, compared to what’s coming.   “Around 50, partly cloudy – not a bad day. But everything changes as we get into the weekend,” he said.

Much Warmer Saturday

A deep trough of low pressure will be developing over the eastern Pacific, which Mass says will drive warm air from the south into our region. This will increase temperatures significantly.

“So, as we get into Saturday, it’ll be partly cloudy and dry and temperatures getting up to 58-59 maybe – something like that,” Mass said.

Like Summer Sunday And Monday

On Sunday, Mass says that warm southerly wind will combine with offshore flow from the east.

“Temperatures will surge,” Mass said, “probably into the low 60s at least, maybe even mid-60s.

And then Monday will be even warmer.

“It’s going to be unbelievable: mid- to upper-60s and I think some places, near where the downslope is producing some additional warming on the eastern side of the region, we’re talking about temperatures getting up to 70 – even low 70s,” Mass said.

He says if this feels like a big shift – it is. The past month has been marked by cooler than normal temperatures in western Washington, which have been due to the influence La Nina. Its dominance has brought in lots of northerly flow, with colder air coming in from Canada and the Arctic.

But that’s all changing this weekend.

“So, a real warm up. And there’s not going to be any precipitation at all on Saturday and Sunday, that’s guaranteed,” Mass said.

To hear the full conversation – including how the same weather systems producing warmth here will cause heavy rain in California this weekend and what that all means for water resources – you can click on the 'play' icon at the top of this post. 

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, and a popular weather blogger. You can also subscribe to podcasts of Weather with Cliff Mass shows, via iTunes 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