Latest National Weather Service guidance and ensemble model runs place Seattle’s May 17 high in the low-to-mid 60s, anchoring the closely matched 62–63 °F and 64 °F+ outcomes. Persistent onshore flow from the Pacific keeps afternoon temperatures moderated while a weak upper-level ridge provides modest warming, producing a narrow probability distribution centered near climatological norms for mid-May. Recent model shifts have narrowed the spread between the 60–61 °F and 62–63 °F bins, reflecting reduced uncertainty in boundary-layer mixing and cloud-cover forecasts. With resolution occurring within 24 hours, traders are weighting the next model update cycle heavily as any deviation in wind direction or marine-layer depth could quickly reprice the 60–64 °F band.