The market’s overwhelming consensus on a Seattle high of 58-59°F for May 16 stems directly from National Weather Service station observations that recorded a peak in that narrow range under stable onshore flow and a cool marine layer typical of early May. These conditions suppressed daytime heating despite clear skies, producing temperatures right at or slightly below the month’s long-term average. Traders quickly incorporated the verified readings from official reporting networks, driving implied probability to essentially 100 percent. Only an extremely rare post-event data correction or reanalysis by NOAA could alter the outcome, an event with negligible historical precedent for daily temperature records.