Heat wave settling in across Northwest; Portland likely to hit 100 Sunday

The first heat wave of the summer is making for a toasty weekend across the Pacific Northwest, with a cool-down not projected until Tuesday.

The latest forecast from the National Weather Service continues a heat advisory for all of Western Oregon and Western Washington, plus parts of south-central Oregon and Central Washington, through 10 p.m. Monday. Daytime highs are expected to be from 90 to 102 degrees in Western Oregon, with lows in the upper 50s to mid 60s.

Off-shore flow (wind bringing heat from the interior to the coast) brought unusually high temperatures to the Oregon Coast on Saturday, according to the National Weather Service:

Highs in the Willamette Valley will drop to low to mid-90s on Monday, and then down to seasonal upper 70s by Tuesday, according to the National Weather Service.

There are no Multnomah County cooling centers open this weekend, because overnight temperatures are expected to dip into the 60s. But three public libraries will stay open later than usual. They include the Central branch, the Holgate branch in southeast Portland, and the Gresham branch on Miller Avenue. They’ll stay open until 8 p.m. on Saturday and Sunday.

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For those seeking relief in cool waters, the weather service urges extreme caution: While the air may be warm, water temperatures throughout Western Oregon and Washington may still be in the 40s and 50s, and that could cause shock.