The setup was truly perfect. But the details weren't. A few adjustments and some parts of King County could've pushed 120 degrees. Kent Hill and Maple Valley hit 100 degrees at 9am, while other areas were way behind. Entirely east wind driven. The GFS had SeaTac hit 120+ degrees. Entirely possible if the East wind didn't die out. The temperature aloft most certainly supported it.
Probably. 90s are a given nowadays but it wasn’t always that way. Even with how much the climate is warming that 2021 caliber heatwave probably won’t happen again for a decade or two atleast. Never say never but that was truly a perfect storm.
I’m sure some low 100s are probably coming in the next 5-10 years in Puget sound but getting 3 +100s at SEA and hitting 108 or higher was extremely anomalous. More anomalous than any weather event any of us has seen in western WA. It’s hard enough getting one +100 in a year thankfully.