National Weather Service forecasts currently call for a Seattle high of 62°F on May 17 under typical springtime onshore flow that draws cool marine air inland. This pattern, driven by a weak pressure gradient and lingering low-level moisture, limits afternoon warming while allowing modest variability from cloud breaks or wind shifts that could push readings into the low 60s or briefly higher. Model consensus from recent runs keeps most guidance clustered between 60–64°F, explaining why the 62–63°F outcome leads with 38.5% implied probability, closely followed by 64°F or higher at 30% and 60–61°F at 26.5%. Historical May averages near 65°F underscore how the present setup remains slightly cooler than climatology, with final resolution hinging on the official Sea-Tac Airport observation.