The Pacific Northwest is bracing for a scorching heatwave, with temperatures soaring into the 80s and 90s this week. This is a stark contrast to the usual cool and rainy weather the region is known for. The heatwave is a result of higher pressure aloft over the Rocky Mountains, which is building towards the Pacific Northwest. The associated southerly flow aloft, combined with weakening surface onshore flow from the Pacific Ocean, will result in significant warming. This will lead to high temperatures across Washington, with the usually warmer locations rising into the lower to mid-90s. Seattle-Tacoma International Airport (SEA) has already hit 90 degrees or better twice this year, and it's possible that SEA could reach 90 again mid-week, though it's unlikely to break the record of 100 degrees set in 1994. The heat will also exacerbate the ongoing dry conditions, enhancing the threat of wildfires. Last week, the season's first roadside fire occurred along SR 525, and outdoor burn bans are in place for most Western Washington counties and cities. The heat will also draw wildfire smoke north from Oregon into Western Washington, leading to poor air quality and potential health concerns. The most vulnerable are the very young, the elderly, and those with respiratory and heart conditions. To find relief from the heat, people are advised to visit air-conditioned facilities like large shopping malls, theaters, libraries, and other such locations. Area waterways also offer the opportunity to cool off, but it's important to wear a life jacket for safety. The heatwave is expected to end later this week, with cooler low-level onshore flow from the Pacific bringing back night and morning marine cloudiness and dropping high temperatures mainly into the 70s. This rollercoaster of Western Washington summer hot days followed by a cool-down, then warming up again, is likely to continue into August.
