**Recent National Weather Service and model consensus point to a Thursday night low of 51–52°F in Seattle, aligning with the market’s leading 52–53°F bin (47% implied probability) and supporting the secondary 50–51°F outcome (27.5%).** Persistent upper-level troughing and onshore southwesterly flow have maintained a marine-influenced regime, with low stratus and cloud cover limiting nighttime radiative cooling. A frontal system arriving Thursday is expected to bring widespread rain (60–90% probability after midday) and keep temperatures from dropping sharply, consistent with climatological September lows near 51–52°F at Sea-Tac. Ensemble guidance shows modest spread, with some members allowing brief clearing that could nudge the minimum a degree or two lower, which explains the 22.5% probability assigned to 45°F or below. Warmer outliers (64°F+) reflect residual uncertainty around timing of any breaks in the cloud deck or weaker frontal effects, though official point forecasts converge tightly around the mid-50s. Traders are weighting the latest NWS guidance and short-range model runs heavily, as resolution occurs within hours and additional forecast updates will be limited before the period ends.