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Rain expected to bring relief to allergy sufferers after record-smashing heat

A view from Orcas Island on Feb. 17, 2019.
Tim Durkan
Tim Durkan Photography
A view from Orcas Island on Feb. 17, 2019.

A weather front approaching the Puget Sound region on Friday morning held the promise of precipitation sure to be welcomed by residents suffering from watery eyes, sinus pain, coughs and running noses.

Many people’s allergies were triggered this week when a sudden storm of tree pollen was brought on by record heat.

Hopefully that will ease up at least a bit as KNKX weather expert Cliff Mass says wet weather is on its way.

“I suspect by dinnertime, rain will spread into Puget Sound,” said Mass, a professor of atmospheric sciences at the University of Washington. “It’s not going to be heavy rain, but it will rain.”

He predicts the rain will probably be done by Saturday morning, but there will be plenty of clouds this weekend and quite a bit of wind.

“I expect winds to gust up to 20 to 30 miles per hours at least,” he said.


He says Saturday will be a transitional day, with a few showers sticking around in the morning, partly cloudy skies and temperatures only getting into the upper 50s.

“So, much (cooler) than we saw before,” Mass said.

On Sunday, he says, expect mostly sunny skies and temperatures inching up to the comfortable range, around 60. “So, actually, not a bad weekend.”


Mass says next week’s weather will be relatively boring here.

“Virtually all of the weather is going into California, the jet stream is going down there. And we’ll have a few intermittent periods where a few bands of showers, a weak front or two will come through,” Mass said.

“Temperatures will be in the upper 50s, a few showers, but some nice days as well. So, pretty temperate.”


More exciting, he says, is the possibility of aurora visible in the region on Saturday night.

“There is a solar storm going on right now,” Mass said Friday morning. “Material from the sun is rapidly propagating towards earth.”

And he says the weather should cooperate.

“I think we’ll be partly cloudy, so it may be visible.” 

Mass says take a look later in the evening on Saturday or in the early hours of Sunday morning.

“Look to the north,” he said, adding that they are spectacularly colorful. “We have a real chance of seeing one. Be on the lookout.”  


Last week, Mass predicted extraordinary warmth in the days ahead. That forecast was more than fulfilled as the Puget Sound region charted record-smashing heat. When temperatures reached 78 degrees on Wednesday, it was the first time since 1894 that Seattle saw three consecutive days in March above 75 degrees. And on Tuesday, the mercury hit 79 degrees at Sea-Tac, officially the hottest winter day on record, going back 125 years.

“It was not only the hottest winter day,” Mass said, noting that it came in the last few days of winter, so perhaps not all that extraordinary. “But it was the hottest March day on record – for any March, going back to the 1890s. That’s another big record.”

He also says seeing two days in a row getting to 79 degrees at Sea-Tac got his attention.


Mass says the main reason for the heat was strong easterly flow, which is flow going from the east to the west. This came from a highly unusual atmospheric configuration, with high pressure to the north and low pressure to the south. It produced that key feature: strong easterly flow, from Eastern Washington into Western Washington.

“And as that air sank on the Cascades, it was compressed and when it gets compressed it warms,” Mass said. “And that really gave us that warm temperature spike that produced extraordinary temperatures here in Seattle.”

Mass notes that Seattle’s temperatures were actually much higher than San Diego’s last week.

“So the bottom line of all this is, we had relatively warm air over us, but it’s the downslope flow that really surged us into record territory,” he said.


The heat also caused an explosion of tree pollen, which many people in the region felt as they suffered from allergies.

Mass notes that the record cold temperatures in February here lasted into early March, which kept plants and pollen down. But the sudden warming into well-above-normal heat this week caused trees to start releasing pollen. And Mass says this was exacerbated by extremely dry air from the downslope flow and a complete lack of precipitation.

“So there was nothing taking the pollen out of the air. And then to make it even worse, we had strong easterly winds – the winds were gusting to 20 to 30 mph,” Mass said.

This caused clouds of pollen coming off trees, some resembling smoke.

He has a video of one on his blog.

“It looked like the trees were on fire, from all of the pollen that was ejected into the air,” Mass said. “So it was in some sense the perfect storm for pollen.”  

To hear the full conversation, 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