National Weather Service forecasts and model consensus have positioned Seattle's May 20 high temperature in the mid-60s as the most probable outcome, driving the 60% market-implied odds for 66-67°F. Pacific maritime air and a building high-pressure ridge suppressed afternoon warming, keeping readings near seasonal averages for the Puget Sound region while limiting the chance of stronger solar heating. Ensemble guidance from NOAA showed limited spread around 65-67°F with minimal risk of exceeding 68°F under stable steering patterns. The slim 27.5% probability attached to 68°F or higher reflects residual uncertainty in boundary-layer mixing and any late-day clearing, though official observations from Sea-Tac and surrounding stations will determine final resolution.