Recent forecasts from multiple models indicate a high of 66–67°F in Seattle on September 28, aligning with the market's leading 46.5% implied probability, driven by a ridge of high pressure promoting mostly sunny conditions and light southerly winds. Ensemble guidance shows modest warming potential into the upper 60s if afternoon insolation strengthens, supporting the closely trailing 37% odds for 68–69°F, while increased marine layer influence or earlier cloud build-up could cap readings at 64–65°F. Historical September norms near 66°F provide climatological context, though late-month variability from Pacific systems introduces uncertainty. Traders are monitoring updated National Weather Service runs and observational data through the weekend for resolution signals on exact peak temperature.