Recent NWS and ensemble forecasts indicate a passing upper-level trough and marine air surge will bring scattered showers and increased cloud cover to the Seattle area overnight into August 23, limiting radiational cooling and supporting minimum temperatures near 58–61°F at Sea-Tac and downtown stations. This setup aligns with the closely matched market probabilities for the 58–59°F and 60–61°F bins, as model guidance shows modest spread in dewpoint recovery and wind speeds that could shift the low by a degree or two. Historical climatology places typical late-August lows near 57°F, but the current cool anomaly and higher humidity reduce the chance of sub-56°F readings. Updated NWS discussions and 00Z/12Z model runs over the next 12–18 hours will provide the key data for refining the overnight minimum.