Latest National Weather Service forecasts for Seattle indicate overnight lows near 58–61°F on August 22, driven by a passing upper-level low and associated front that is introducing cooler marine air and increased cloud cover. This setup limits radiational cooling overnight while scattered showers may further moderate temperatures, keeping readings above seasonal averages in some model runs but preventing stronger warming. Ensemble guidance shows modest spread tied to exact timing of the frontal passage and boundary-layer moisture, which explains tight clustering around the 58–61°F bins. Historical August minima in Seattle typically range from the mid-50s to low 60s under similar synoptic patterns, underscoring why traders view outcomes outside this window as lower probability ahead of final observations.