Trader consensus overwhelmingly favors a high temperature of 57°F or below in Seattle today, with 99.6% implied probability, driven by the National Weather Service forecast calling for a maximum of 53°F amid persistent onshore flow, low stratus clouds, and likely showers or thunderstorms through early afternoon. This cool-down follows early May's record-breaking warmth above 80°F, as a weakening upper-level ridge allows cool Pacific marine air advection, capping daytime heating per model ensembles from NOAA. Observations at Seattle-Tacoma International Airport show morning temperatures in the upper 40s to low 50s under overcast skies. Realistic challenges include unexpected afternoon cloud clearance and stronger solar insolation pushing toward 58°F, though precipitation odds (60%) and marine layer persistence make this unlikely; final airport readings will resolve the market by midnight.