Recent National Weather Service guidance and ensemble models highlight persistent uncertainty in Seattle’s overnight minimum for August 23, driven by a transition to cooler conditions with scattered showers and variable marine-layer influence under a weakening high-pressure ridge. Key scientific factors include the degree of radiational cooling, modulated by cloud cover and stratus; the strength and timing of onshore flow from Puget Sound that advects cooler marine air; and any precipitation that could suppress temperature drops. Historical August lows average near 57 °F, but model spreads currently favor outcomes clustered in the upper 50s to low 60s, with traders assigning nearly equal implied probabilities to extremes above 72 °F or at or below 53 °F. Updated forecast runs and local observations over the next 12–24 hours will likely narrow these ranges.