Recent National Weather Service forecasts and supporting model runs point to a Monday high in the mid- to upper 60s under mostly sunny to partly cloudy skies, aligning with the market’s tight clustering around 66–69°F. Light southerly winds and minimal cloud cover should permit efficient daytime heating after a cool overnight low near 45–50°F, while the region’s marine air mass and September climatology cap extreme warming. Minor model spread on afternoon cloud timing and exact wind direction creates the narrow gap between the 68–69°F and 66–67°F bins. Traders appear to weigh the upper end of official guidance more heavily, consistent with the modest 45.5 % implied probability on the warmest bracket, with resolution hinging on the final Sea-Tac observation.