**An incoming early-September Pacific storm system is the dominant driver suppressing Seattle's high temperature on September 2, 2026, to the mid-60s.** Official and model consensus from sources including the National Weather Service and private forecasters points to widespread cloud cover, steady rain (with totals of 0.1–0.25 inches), and southerly winds gusting to 25 mph, which limit daytime heating and keep the maximum well below the 1991–2020 climatological average of ~74°F. Multiple forecasts issued September 1 converge on a high of 64–67°F, aligning with the market's leading bins (66–67°F at 37.5% implied probability, 64–65°F at 23.5%, and 68–69°F at 27%). The storm's timing—rain becoming likely by midday—further caps warming, while historical analogs show similar synoptic setups rarely exceed the upper 60s. Traders appear to be weighting the latest model runs and the certainty of precipitation over any residual uncertainty in exact steering or intensity, resulting in very low odds for readings above 70°F or below 62°F. Updated National Weather Service briefings and new model cycles expected overnight will be the next key data points for position adjustments.