Pacific Northwest rainfall nears historic lows this October

October rain has been slow to arrive across parts of the Pacific Northwest, leaving cities from Portland to Vancouver, B.C., with rainfall totals well below normal.

Seattle is approaching the end of the month with the possibility of recording one of its driest Octobers in more than 130 years, according to the Seattle Times.

Recent rain has helped in some areas, but the month’s dry start has left a substantial gap. Here’s how conditions compare across the region.

How dry has October been in Washington?

Seattle-Tacoma International Airport had received just 0.28 inches of rain through the weekend preceding Oct. 26, according to KIRO Newsradio meteorologist Ted Buehner. The airport typically receives nearly 4 inches during the full month.

Olympia was also running well behind, with 0.58 inches recorded over the same period. Its driest October finished with 0.27 inches in 1917.

Seattle’s historical benchmark dates to 1895, when downtown observations recorded only 0.02 inches for October. At Sea-Tac, October 1987 brought just 0.31 inches.

Those records come from different observation locations, a distinction that matters when comparing Seattle’s rainfall history.

Additional rain before Oct. 31 will determine where this October finishes.

Is Oregon seeing a similar rainfall shortage?

Portland’s dry start was followed by a noticeable increase in rain late in the month.

Preliminary National Weather Service observations showed 0.78 inches through Oct. 25, including 0.67 inches that day alone. Even with that rainfall, Portland remained 1.79 inches below normal for the period.

That single day supplied about 86% of the airport’s month-to-date rainfall, showing how little had fallen during the preceding weeks.

How far north does the dry weather extend?

British Columbia’s south coast has also experienced an unusually dry October.

According to The Weather Network, Vancouver had received 9.5 millimeters through Oct. 18, about 8% of its full-month average. Victoria had recorded just 2.6 millimeters, roughly 3% of its October average.

Both cities were on track for potentially record-setting dry months when that report was published Oct. 19. Those figures describe the earlier part of October, rather than final monthly totals.

Why has October been so dry?

According to The Weather Network, high pressure over the northeastern Pacific has pushed fall storms toward Alaska and the Yukon, keeping rain away from British Columbia’s south coast.

Several communities across the western Pacific Northwest remain short on rain. Rainfall in October’s final days will determine how close they come to historic lows.