Recent National Weather Service forecasts place Seattle’s September 4 high in the mid-to-upper 60s under a cool, unstable air mass tied to an upper-level low drifting inland. This setup favors partly to mostly cloudy skies with only modest daytime heating and a 20–40% chance of light showers, limiting solar warming and keeping readings well below the 73°F climatological average. Ensemble guidance shows little spread, but small differences in cloud timing or boundary-layer mixing can easily shift the daily maximum across the 64–69°F range that dominates market-implied probabilities. With resolution only two days away, the next model runs and any updated NWS discussion will be the key catalysts for further price movement.