It’s been the wettest early fall on record in the Seattle area — and more rain is coming

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The Armstrong family walks up a hill in pouring rain Sunday at Gas Works Park in Seattle. They had come hoping to take a family photo. (Amanda Snyder / The Seattle Times)

You’re not imagining that it’s been unusually wet, even by Seattle’s notoriously rainy standards.

With 18.91 inches of rain recorded at Seattle-Tacoma International Airport between Sept. 1 and Nov. 28, and another atmospheric river of rain due on Tuesday, it’s looking like this will go down as the wettest early fall on record.

The second wettest September through November period in Seattle was recorded in 2006, when 18.61 inches of rain were recorded at the airport, according to the National Weather Service in Seattle.

Instead of the constant drizzle of some past years, this year’s rain has come mostly in torrents from atmospheric rivers, or Pineapple Expresses as they were once known, that have flooded rivers and lowlands and already water-soaked earth.

The two most recent atmospheric rivers, late last week and over the weekend, drove a lot of the extreme flooding we’ve seen in the area, weather service meteorologist Kirby Cook said.

“It’s the wettest early fall we’ve had in Seattle in a long, long time,” he said early Monday. “And in some areas, like Bellingham, it will be the wettest November on record.”

However, the flooding that hit northwest Washington this weekend doesn’t appear to be as severe as when extreme weather hit the region earlier this month.

Residents in Sumas and Everson were asked to evacuate voluntarily Saturday night. Both towns near the Canadian border saw extreme flooding earlier this month that caused an estimated $50 million in damage in Whatcom County.

“It appears that we are through the worst of it for the Everson/Nooksack area,” Everson Mayor John Perry wrote in a Facebook post Sunday night. “We could still see a few isolated areas where the level raises slightly, but for the most part it looks like we are improving.”

Many rivers in the Pacific Northwest were expected to remain in flood stages through the end of Monday, Cook said.

And even once they recede, it appears another river of rain is due to land on Tuesday and Wednesday, he said.

That weather system will have the most impact over the Olympic and Cascade mountains, Cook said. It’s weaker than the two we just had, he said, but still concerning in light of the recent rains.

“The concerning part is that there is still an elevated risk for potential landslides, which can continue even after the rain has stopped, so we’ll be keeping an eye on that,” Cook said.

Though we may not get clear blue skies, folks can expect a short break on Thursday and Friday, when we are expected to see a pause in the rain before the next round of wet weather moves in, Cook said.

“It may not be sunny, but we’ll get a little dry period and at least the chance to dry out,” Cook said.

Information from the Associated Press was included in this report.

Christine Clarridge: 206-464-8983 or cclarridge@seattletimes.com; .