Official forecasts from the National Weather Service and AccuWeather place Seattle’s May 17 high near 62–63 °F under partly cloudy skies and light northerly flow. This positioning stems from a modest marine push that limits daytime heating while allowing brief sun breaks to nudge temperatures into the low 60s. Trader probabilities cluster tightly across the 60–64 °F bands because model runs differ on cloud timing and onshore breeze strength, each of which can shift the peak by 2–3 °F. Historical May highs average 65–67 °F at Sea-Tac, so the current setup sits slightly below climatology yet remains well above the cooler pattern that held earlier in the week. Updated model guidance expected overnight will clarify whether additional clearing pushes readings toward 64 °F or keeps them capped in the low 60s.