Recent National Weather Service guidance and ensemble model runs position upper-70s to low-80s highs as the most probable outcomes for Seattle on August 20, aligning with the market's heavy weighting on the 80–83°F bins. These forecasts reflect typical late-summer maritime influences, including onshore flow and marine-layer moderation that cap daytime maxima near the climatological average of roughly 76°F while allowing modest warming under partly sunny conditions. KING5 and AccuWeather outlooks converge on 79–82°F, with low precipitation chances supporting limited convective cooling. Traders appear to factor in model spread and potential afternoon clearing that could push readings a degree or two higher, while discounting rarer warmer scenarios above 85°F given persistent Pacific Northwest coastal effects. Updated model runs and official observations later today will refine resolution probabilities.