The first weekend in August is statistically one of the driest and warmest weekends in the Pacific Northwest. It also marks the height of outdoor summer fun in Seattle as Seafair’s hydroplane races hit the water and the Blue Angels show off their daredevil moves in the skies above.
KPLU weather expert Cliff Mass says this year’s Seafair Weekend forecast is for cooler than normal weather and even some rain.
“But the rain’s going to hold off till the end of Sunday, so I think most activities will be fine,” Mass said.
The basic situation, Mass says, is that there’s an upper-level trough of low pressure approaching the Northwest. It’s bringing in temperatures that are 5 to 10 degrees lower than typical.
“It’s unusual for this time of year, but it’s there. And as that trough approaches, it’s going to bring cooler than normal air into us. And later in the weekend, I think we’ll see rain that’ll extend into Monday,” Mass said.
He says temperatures on Saturday will probably get up to 68 degrees or 69, under mainly sunny skies.
“So Saturday’s going to be quite a good day,” he said.
On Sunday, temperatures will get up to about the same level, but with increasing clouds during the afternoon.
“And rain could be in on Sunday around dinnertime. So, later in the afternoon you have a real danger of precipitation. But the first part of the day should be fine,” Mass said. There could even be some thunder and lightning.
Monday will bring a lot more rain and cooler temperatures, with highs in the upper 60s. “That’ll probably be the wettest day,” Mass predicted.
But during mid-week, it looks like a ridge of high pressure will develop. So temperatures should surge back into the 70s again.
He says overall, the forecast could be worse.
“The rain’s not going to come in till the end of Sunday, so Saturday will be great. Sunday morning, where a lot of the activities are going on, should be fine,” Mass said.
“It’s just that BBQ outside. Sunday evening could be problematic; That’s when people should be worried,” 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.
