**An upper-level trough and associated disturbances are steering cooler, moister air into western Washington, with forecasts from the National Weather Service and other models converging on a Saturday high in the mid-to-upper 60s.** Persistent cloud cover, morning rain or showers, and a chance of afternoon thunderstorms limit solar heating and promote evaporative cooling, keeping readings below the late-August climatological average of ~75°F. Light winds and the moderating influence of Puget Sound further cap peaks, producing the tight clustering of market-implied probabilities around 66–69°F. Later-day partial clearing could allow brief warming into the low 70s in some model runs, which explains the secondary weight on 70–71°F, while the overall trough signature makes outcomes above 72°F or below 64°F less likely. Updated NWS guidance and ensemble consensus released in the past 24–48 hours continue to reinforce this narrow temperature band ahead of the August 29 observation window.