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Last Blast Of Summer Heat This Weekend Before Fall Returns Next Week

Tim Durkan

Don’t put away that sunscreen just yet.

Temperatures are expected to shoot back up into the upper 70s and even 80s for the last weekend of summer, topping off what will likely go down as the warmest summer in Seattle history.

“It’s going to get hot again, but just temporarily,” said KPLU weather expert Cliff Mass, adding the warm weekend will be “followed by a period of rain and cooler temperatures.”

‘A Definite Warm-Up Through Sunday’

Friday began with a bit of rain and cloud cover, but those conditions were expected to thin out later in the day and into Saturday.

“We should see partly sunny skies [on Friday], and then Saturday is going to be phenomenal,” Mass said. “Sunny, pretty much clear, temperatures zooming back up into mid-70s, upper 70s for some.”

Mass says the interior may even see temperatures in the 80s on Sunday.

“So, a definite warm up through Sunday,” he said.

Mass predicts the only place that will see some clouds will be the coast. That’s where clouds will start forming on Sunday as marine air pushes up the coast into southern Oregon and central Washington.

“So that’s the only negative over the weekend,” Mass said.

Fall Weather Returns Next Week

Early next week, we’ll see a dramatic drop in temperatures Wednesday and Thursday with an almost certain chance of rain.

“So there’ll be a major transition, from having mainly ridging over us with warmth and clear skies, to a deep trough,” Mass said. “And we will know that we are back in fall, starting somewhere around Wednesday or Thursday.”

A Record-Breaking Summer Still In The Making

Tuesday’s equinox marks the official start of fall following what will likely go down as Seattle’s warmest summer in history. Summer is officially measured from June 21 to Sept. 21.

“We know that July and August were the warmest in the whole record for a number stations around Washington, including Seattle,” Mass said. “It appears that it’s been warm enough the first part of September that we should see the record-breaking summer.”

Still, with a few days of data still left to gather, Mass wasn’t ready to make that official pronouncement just yet.

“I think we have it in the bag, but it’s a little early to be sure,” he said.


The weekly KPLU feature "Weather with Cliff Mass" airs every Friday at 9 a.m. immediately following BirdNote, and twice on Friday afternoons during All Things Considered. The feature is hosted by KPLU 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 a podcast of “Weather with Cliff Mass” shows.

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