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Thank 'The Blob' For This Warm Summer And The Sunny Weekend Ahead

Tim Durkan
"September sunsets — the best."";

The record-breaking summer isn’t giving way to fall just yet. Another gloriously sunny Northwest weekend is in store, says KPLU weather expert Cliff Mass.

“We will have a really beautiful weekend — no precipitation, clear skies and warming temperatures,” Mass said.

A Perfect Weekend

Mass says temperatures will climb and reach the mid-to-upper 70s on Friday.

“Full sun, very nice day,” Mass said.

Then things will progressively warm over the weekend, reaching into the low- or even mid-80s with the warmest temperatures coming on Sunday.

“And it’s even going to be in the 80s on Monday,” Mass said. “So we’re going to have a perfect weekend.”

One sign of the looming fall is upon us, however: much cooler temperatures at night as the skies stay dark longer. And Mass says the lack of cloud cover is exacerbating that phenomenon, causing extreme daily temperature swings.

“Clear skies with dry air has enabled temperatures to fall into the 30s. It went down to 37 in Olympia and a few places even got near freezing last [Thursday] night,” Mass said.

Warm, Humid Summer Caused By ‘The Blob’

One of the reasons it’s been so warm summer is “the blob,” says Mass.

That’s what meteorologist are affectionately calling a warm patch of water off the Northwest coast.

“These warm waters have been extraordinarily persistent. They lasted through the winter into the summer,” Mass said. “In fact, we believe one reason this summer has been so warm is that the warm waters offshore have warmed the air as it’s come off the ocean into the Northwest.”

Mass says the blob was caused by the persistent pressure system that locked in so much fog last winter. It also created an area of water that is 2 to 3 degrees Celcius warmer than normal, because it kept storms down and caused fewer waves and less mixing of the upper Pacific. The mixing normally brings colder water from the depths closer to the surface.

The blob also made for a more humid summer as warmer air next to warm water pulls more moisture, causing higher dew points.

The Blob + El Niño = Warm Autumn, Winter Likely

Mass says meteorologists expect the blob to remain in place at least into the fall and maybe even into the early winter. That combined with the El Niño that’s in the long-term forecast could spell a very warm autumn and winter ahead.

“The combination of this residual warm water, the blob, and this developing El Niño could very well cause this coming fall and winter to be substantially warmer than normal. We’re talking 2, 3 degrees Fahrenheit above normal [for average temperatures], which, meteorologically, is really quite a lot,” Mass said.

But Mass says experts don’t know if the pattern that caused the high-pressure system will lock in again. So don’t worry too much about a return of fogmageddon.


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