The Northwest Bakes as the Region Faces Hotter, Longer Heat Waves Inland areas farther from the coast are facing particularly dangerous conditions this weekend, forecasters say.

The Northwest Bakes as the Region Faces Hotter, Longer Heat Waves

Inland areas farther from the coast are facing particularly dangerous conditions this weekend, forecasters say.

By Isabelle Taft

July 21, 2024, 5:00 p.m. ET

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As a heat wave lingers in the Pacific Northwest, people in parts of Washington, Oregon and Idaho who are farther from the coast may see dangerously high temperatures near 110 degrees before the weekend is over.

Parts of the three states, along with northern Nevada, are under an extreme heat warning from the National Weather Service, continuing a hot July for the whole region, where extreme heat was linked to hundreds of deaths in 2021.

In Boise, Idaho, Sunday’s forecast high of 107 degrees is about 10 degrees above normal and will add to a 13-day stretch of highs of 99 degrees or above in southern Idaho, said Les Colin, a senior forecaster at the National Weather Service office in Boise. On most of those days, the temperature was above 100. By early afternoon on Sunday, the temperature had already hit 99 once again.

Temperatures there will not drop significantly until the end of the week, according to forecasters. If forecasts hold, Thursday will be the 10th straight 100-degree day, breaking the city’s record for the number of consecutive days with triple-digit temperatures.

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In Spokane, Wash., the high is forecast to reach 106 degrees — it was 102 on Sunday afternoon — with triple-digit temperatures extending through Monday.

In Pendleton, Ore., in the northeast part of the state, the high Sunday was expected to reach 106 before temperatures fall into the 90s by Monday.

Temperatures are more normal in the region’s most populated areas, closer to the coasts. In Portland, Ore., Sunday’s forecast high of 86 is not far off from typical highs for late July, the National Weather Service said. In Seattle, the high of 83 is above average but cooler than recent days.

In western Washington, forecasters expect highs into the upper 70s to return on Monday.

For meteorologists and residents of the region, the extreme heat event recalls the devastating heat dome of 2021, during which overall temperature records were broken by several degrees in many cities and hundreds of people died.

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For Spokane, this heat wave has lasted longer than the heat event in 2021, but the high temperatures have been lower and, significantly, nights have been cooler, said Brian G. Henning, the director of the Gonzaga Institute for Climate, Water and the Environment.

“Bodies are able to recover,” he said. “I think that’s one of the reasons why we’re having fewer visits to the emergency department.”

Scientists said that climate change appears to be increasing the intensity and duration of heat events in the Northwest.

“We’re used to heat, we’d get some extreme heat, that would be normal,” Dr. Henning said of Spokane. “It’s just that now, the severity is worse, and the duration is longer.”

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Paul Loikith, an associate professor of geography at Portland State University, said it was safe to assume that climate change had added about three degrees to the summer temperatures in the Pacific Northwest — on days of “extreme heat” and normal days alike. That means cool days are not as cool, and warm days are warmer.

The current heat wave has also aggravated fires in the region, said Mr. Colin, the senior forecaster in Boise. That city’s Sunday forecast includes “areas of smoke,” mostly produced by two wildfires in eastern and central Oregon.

“When there’s an existing fire, which is created by lightning or even by people, those fires tend to become very active, and spread rapidly,” Mr. Colin said.

But the smoke, which partly filters the sun, will reduce high temperatures by a couple of degrees on Sunday and Monday, the Weather Service predicted.

Isabelle Taft is a reporter covering national news and a member of the 2024-25 Times Fellowship class, a program for journalists early in their career. More about Isabelle Taft