Latest National Weather Service guidance and regional model runs point to a Seattle high near 80–82°F on August 20, driven by gradual clearing of morning marine stratus followed by mostly sunny skies and light northwesterly flow. This aligns with traders clustering probability on the 80–83°F bands amid typical mid-August Pacific moderation, where the Puget Sound’s cool marine layer and onshore breeze limit extremes despite above-normal seasonal baselines around 77–79°F. Key uncertainties include the precise timing of cloud dissipation and boundary-layer mixing, which can shift peak readings by 2–3°F; stronger onshore winds or lingering stratus would favor the lower 80s, while clearer conditions and calm winds support the upper end. Updated NWS point forecasts tomorrow morning will refine these thresholds ahead of resolution.