Strong El Niño conditions, with Niño 3.4 anomalies near +2.6°C and over 90% odds of a very strong event through fall 2026, represent the dominant driver tilting trader sentiment toward below-average Seattle precipitation. NOAA and regional outlooks favor drier-than-normal conditions across the Pacific Northwest in September–November, consistent with suppressed storm tracks and warmer, more stable air masses typical of El Niño onset. Historical analogs and model guidance show September totals often clustering near or below the 1.8–2 inch climatological mean as the rainy season transition begins, though early-month variability and potential late-September atmospheric rivers introduce spread across the 1–3 inch bins. The closely matched leading probabilities reflect ongoing uncertainty in exact monthly accumulation amid evolving forecast guidance.