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Know the West

Yes, 90 degrees can be dangerous

From a jump in ER visits and gun violence to fears for maternal health, the Northwest’s May heat wave shows the dangers of more moderate, early heat waves.


As 90-degree temperatures bore down on the Pacific Northwest in May, real-time reporting to the Centers for Disease Control showed that heat-related emergency room visit rates were 40 times higher than the previous weekend. Though state officials caution that the data is preliminary, Oregon and Washington confirmed 160 heat-related ER visits from May 12 to 15. In Washington, the average during a similar period is about 7. At least 10 people in that state were hospitalized. And heat-related emergencies were just one public health impact of the four days of record temperatures: Heat waves are linked to increased violence, poor school performance and worse health overall.

During a heat wave last July, Gabe DeBay, medical services officer with the Shoreline Fire Department, checks the blood pressure of an unhoused man at a tent encampment in Shoreline, Washington. Heat in the Pacific Northwest is already higher than normal this year. Unhoused people and outdoor workers are among those at highest risk in more moderate, early heat.
David Ryder/Getty Images

That temperatures in western Oregon and Washington hit the low- to mid-90s is not in itself remarkable. But the timing of the heat wave was. This time of year, “our bodies aren’t acclimated to those temperatures,” said Adelle Monteblanco, a public health professor at Pacific University, near Portland, who researches extreme heat. This makes even moderately high heat more dangerous: Health risks increase when temperatures are higher than locals are used to, not just when they reach triple-digits. Some communities faced temperatures nearly 30 degrees higher than normal for mid-May — a difference comparable to nearing 110 degrees during a July or August heat wave.

In May, people’s behavior has not adapted yet, either, Monteblanco said. After a long, dark winter, “I think people probably took risks they shouldn't have,” and did things they’re less likely to consider during more extreme summer temperatures. “They probably weren't drinking enough water. They ran their errands during the hottest part of the day. They didn't wear the right clothing, and they didn't pace themselves.”

 “I think people probably took risks they shouldn't have.”

Heat is the top weather-related killer in the U.S., but its effects remain widely underestimated, even as temperatures rise: Earlier, longer and hotter heat waves are an expected result of climate change. “We often talk about it as a silent killer,” Monteblanco said. “We can’t see it. It’s slow-moving. But if you are unhoused or an outdoor worker, it doesn’t look so invisible anymore.” Members of those groups are also among those at higher risk from earlier heat.

In addition to direct health impacts, heat waves are known to increase gun violence, as well as domestic and other violence. “Think about how testy you get when you get hot,” said Ann Loeffler, a public health official in Multnomah County, which includes Portland. Though drawing direct links to specific incidents is difficult, Portland police reported a rash of shootings that left eight people injured and one dead. Loeffler also noted at least eight suspected drug overdoses that weekend. Although a direct connection is hard to draw, the CDC says heat exposure can contribute to overdose deaths. News reports show at least six people in Oregon and Washington drowned, another known impact of high heat.

Monteblanco, whose research focuses on pregnant people and children, is also concerned about longer-term impacts: Prolonged heat can cause pre-term births, low birth weight and gestational diabetes. “Heat waves are going to exacerbate our maternal health crisis,” she said, referring to recent and significant increases in maternal deaths, especially among people of color.

Loeffler said her office did everything it could to protect residents, distributing water and sunscreen to unhoused people and helping residents find air-conditioned libraries and malls. But facilities that are normally open in summer were not available: Many water features haven’t opened yet, nearly a third of the city’s libraries are closed this year for construction, and county officials decided not to open additional cooling centers, citing easier post-pandemic access to other public spaces.

“We have to prepare our cities for hotter temperatures,” Monteblanco said, surprised that some cities didn’t do more. “Cooling centers are central to preparation, response and resilience.” But interventions to help people protect themselves also don’t go far enough, she said. “At this stage, I’m just so eager to vote for policy changes.” She said useful steps include the newly passed Pregnant Workers Fairness Act, which advocates say will help protect pregnant workers from heat, and the recently introduced Black Maternal Health Momnibus Act, along with anything that reduces dependence on fossil fuels.

“The risk is only going to continue to grow,” she said.

Sarah Trent is an editorial intern for High Country News based in southwest Washington. Email her at [email protected] or submit a letter to the editor. See our letters to the editor policy.