Trader sentiment on Seattle's March 28 high temperature reveals a tight bimodal split, with 51°F or below and 70°F or higher each at 25.5% market-implied probability, driven by divergent ensemble forecasts from NOAA's GFS and ECMWF models amid spring transitional weather patterns. Official NWS guidance favors cooler outcomes around 52°F, constrained by persistent marine layer stratocumulus clouds and Pacific Northwest low-pressure troughing that suppress diurnal heating in Seattle's cool maritime climate. Warmer 70°F+ scenarios hinge on outlier model runs projecting upper-level ridging and brief sunny breaks, potentially mimicking rare late-March heat events, though historical norms cluster in the mid-50s with limited upside from Puget Sound moderation. Key watch: afternoon cloud evolution per latest 12z model updates.