Latest National Weather Service and NOAA model runs indicate Seattle's August 19 high temperature will likely fall in the mid- to upper-70s°F, with ensemble guidance showing modest warming under weak high pressure tempered by marine air influence from the Puget Sound and prevailing westerly flow. This spread across leading bins reflects forecast uncertainty in boundary-layer mixing and any late-day onshore push, consistent with typical late-summer variability where afternoon temperatures rarely exceed 80°F without strong offshore winds. Historical climatology places average daily maxima near 76°F, providing context for why traders assign the highest implied probabilities to 76–79°F ranges while discounting warmer outliers. Updated model cycles and morning observations tomorrow will supply the final inputs for resolution.