**Latest official guidance from the National Weather Service and numerical models (GFS/ECMWF) shows Seattle-area highs on August 17 centering on the upper 70s, with a narrow spread reflecting typical late-summer variability.** Onshore flow from the Pacific and a moderating marine layer are expected to limit afternoon warming, keeping temperatures near or slightly below seasonal normals despite the broader warmer-than-average summer pattern. Key differentiating factors include the strength and timing of any stratus burn-off, the depth of the marine layer, and subtle shifts in the position of the offshore ridge, which can add or subtract a few degrees depending on how quickly skies clear. These variables explain why trader-implied probabilities cluster tightly around 78–81 °F while assigning only modest odds to outcomes above 82 °F or below 74 °F. Updated model runs and the next NWS forecast discussion will be the primary near-term catalysts for any market movement.