Comment Nearly 40 million Americans are under a heat alert Tuesday as two zones of extremely high temperatures bake parts of the Lower 48. Parts of the Southern Plains from Texas to southern Missouri continue to cook, as they have for most of the summer. But for the Pacific Northwest, the arrival of this blistering heat is more of a shock after a relatively cool summer so far. Across the Pacific Northwest, temperatures are forecast to be the hottest of the summer and aren’t expected to drop until the weekend. In Seattle and Portland, this heat wave could approach record longevity. Both cities are under extreme heat warnings until Thursday night. Seattle could see the mercury reach 90 on four straight days through Friday, while Portland could see afternoon temperatures near 100. Historic flooding sweeps St. Louis residents into their cars and homes The National Weather Service issued heat warnings for millions of people on Tuesday as the Biden administration unveiled Heat.gov, “a new website that provides the public and decision makers with clear, timely and science-based information to understand and reduce risks to health from excessive heat.” The heat wave in the Pacific Northwest comes a little more than a year after all-time records were broken in Seattle and Portland, with high temperatures of 108 and 116 degrees, respectively. The same event set a record high in Canada, where Lytton, British Columbia soared to 121 points. The city burned to the ground the next day. Pacific Northwest heat wave was ‘virtually impossible’ without climate change, scientists find Forecasters in Seattle and Portland pointed out that this year’s heat wave, while not as intense as last year’s, is notable for its longevity. “It’s the duration that’s really remarkable about this event,” said Colby Neuman, a meteorologist at the National Weather Service in Portland. “The most consecutive 95-degree days in Portland on record is six, and we will certainly be on the lookout to approach, tie or surpass that record. In the next few days, we will be around 100.” Portland International Airport hit 98.6 degrees on Monday, and after Tuesday’s predicted high of 101 degrees, the city is expected to be in the 90s by Friday. The forecast high for Saturday is 95 degrees. For now, the city is projected to tie the record. “When we see high levels around 100, hospital visits with heat-related illnesses are certainly much higher than historical levels,” Neuman said. “And with Covid still around, there is a limit to hospital capacity and these events are exacerbating that.” Access to air conditioning is a complex factor that heightens the risk in vulnerable populations such as the elderly and the homeless. In Portland, 78 percent of households have air conditioning, but that number drops to 44 percent in Seattle. Seattle hit 85 degrees on Monday — the average high this time of year is 79 degrees — but each day through Friday should top out at or above 90 degrees. Heat waves, defined as periods of three consecutive days of 90 degrees or greater, are somewhat rare in Seattle. This will mark just the 24th since World War II. Half of these heat waves have occurred in the past 15 years, underscoring the role of human-induced climate change in making heat events more frequent and more intense. Officially, the record for the longest heat wave in Seattle is five days, which was set in both 2015 and 1981. “Take extra precautions if you are working or spending time outside,” the Seattle Weather Service said. “When possible, reschedule strenuous activities for early morning or evening.” The agency called attention to the Washington public service hotline, accessible at 2-1-1, which can provide callers with information about cold shelters and other services. Of particular concern are elevated nighttime temperatures, which will keep unair-conditioned homes uncomfortably warm. Temperatures in Seattle briefly dipped below 70 Tuesday morning. No relief from the heat. Sea-Tac’s temperature dropped below 70° at about 4:50 am. and it’s already back to 70° at 6:25 am. pic.twitter.com/73RfaNgXtM — NWS Seattle (@NWSSeattle) July 26, 2022 In Portland, the low temperature Tuesday was 69 degrees. “There’s a large portion of the population here that doesn’t have air conditioning,” Neuman said. “In the past, people relied on opening their windows to cool their homes. They can’t this time.” By the end of the week, the most extreme heat is expected Thursday and Friday in eastern Washington, where highs could reach 110 degrees, particularly in the lowlands of the Columbia River Basin. Kennewick, Wash., about 50 miles east-southeast of Yakima, could top 112 degrees Thursday and 110 on Friday. Yakima proper will flirt with 110 degrees on Thursday before easing back to 108 on Friday and 105 on Saturday. Because the Dust Bowl was hotter than this heat wave, despite global warming Temperatures of 100 to 110 degrees will be common inland and across northern Oregon. Medford hit a record high of 107 points on Monday, while Dallesport, Wash., on the Oregon border, soared to 108. The heat comes from a ridge of high pressure, or “heat dome,” that is stationed in the northeast Pacific, west of British Columbia. It diverts the jet stream north towards Canada along with any severe weather and thunderstorms. In contrast, weather in the Pacific Northwest is characterized by clear skies and warm, sinking air. Jason Samenow contributed to this report.
