**Strong El Niño conditions, with a 75-98% chance of a record-strength event, are the dominant driver behind trader positioning for Seattle's October 2026 precipitation.** NOAA's Climate Prediction Center assigns equal chances for below-, near-, or above-normal totals across the Pacific Northwest because dynamical models and statistical tools show limited support for the typical El Niño drier signal in October. Historical normals place Seattle at about 3.9 inches, with half of years falling between 2.5-5.1 inches. Early-month model runs indicate a relatively dry start before the storm track potentially activates, creating the observed clustering of market-implied odds around the 1.75-4.75 inch range while keeping tail risks for very wet or very dry outcomes lower. Upcoming weekly and monthly updates from the NWS will likely refine these probabilities as the first Pacific systems arrive.