Oregon heat wave: Willamette Valley could match record of 5 days above 100 degrees

The Willamette Valley has only reached five days straight of 100 degree temperatures once in recorded history — way back in 1941.

From July 13 to 17, Portland baked in five days of triple digits. Salem just missed, topping out at 99 degrees on July 17, 1941.

That historical standard has a chance to be matched over the coming week as forecasts call for every major Willamette Valley city to see near triple digits temperatures across five sweltering days.

“We have a high degree of confidence that we’re going to be very close to triple digits each of these next five days,” said Noah Alviz, a meteorologist for the National Weather Service in Portland. “We could get there, but it’s obviously very uncommon.”

Four consecutive days of 100 degrees is a bit more common — it happened in 1941, 1977, 1981, 1994 and 2023.

How hot will it get in the Willamette Valley?

Most forecast point to temperatures reaching 100 to 105 each day until Tuesday, Alviz said.

The only good news is that t he more extreme temperatures that were in play —up to 110 degrees — now appear unlikely, Alviz said. There’s a 5-15% chance of 110 degrees in Salem, Eugene and Portland at this point. And temperatures won’t approach the state record 117-118 degrees recorded in 2021.

“Right now we’re more concerned about the duration of the heat, rather than how hot it will get,” Alviz said.

Saturday and Sunday appear likely to be the hottest days, clocking in around 104 or 105.

How long will the Oregon heat wave last?

The heat wave is expected to drop back below 100 degrees by Wednesday, when temperatures are currently forecast to reach only the low 90s. Beyond that, Alviz said it would depend on how much the ocean breeze pushes into the valley.

“We’ll cool down once that onshore flow from the ocean breaks through and brings in the sea breeze,” Alviz said. “How much it cools down — into the 90s or the 80s — we’ll just have to wait and see.”

Gov. Tina Kotek declares extreme heat emergency

Gov. Tina Kotek declared a statewide extreme heat emergency on Friday.

"I am urging Oregonians to take every precaution and check on your family and neighbors," she said in a news release.

Kotek said the Oregon Department of Emergency Management will "coordinate all essential protective measures in support of identified disaster areas to protect lives, property, and the environment."

Wildfire danger rises, but red flag warnings unlikely

The heat will bring elevated fire danger, but unlike some other parts of the state, northwest Oregon isn’t forecast to see any red flag warnings. That’s mainly because there aren’t any significant winds forecast to push fire danger to critical levels, Alviz said.

“We could have some somewhat breezy north winds (Friday), but overall the winds really die down as the heat wave moves into place, thankfully,” Alviz said.

Escape from the heat on the Oregon Coast

The best place to escape the heat, as ever, will be the Oregon Coast, where temperatures are forecast to stay in the 70s , with Tillamook and Astoria reaching the 80s.

"They're still forecast to get that onshore flow from the ocean, which will cool things down," National Weather Service meteorologist Shawn Weagle said.

What is a heat dome?

As for what's forecast to cause the heat dome, it's "a very strong ridge of high pressure that pushes the air down and heats it up," Weagle said. "Combined with the strong sunshine this time of year and the hot air mass from the southwest, all those factors come together in this heat dome."

Zach Urness has been an outdoors reporter in Oregon for 16 years and is host of the Explore Oregon Podcast . Urness is the author of “ Best Hikes with Kids: Oregon ” and “ Hiking Southern Oregon .” He can be reached at zurness@StatesmanJournal.com or (503) 399-6801. Find him on X at @ZachsORoutdoors.

This article originally appeared on Salem Statesman Journal: Oregon heat wave: Willamette Valley could match record of 5 days above 100 degrees