An approaching upper-level low is driving cooler, unsettled conditions across western Washington, pushing Seattle's overnight low on August 22 into the upper 50s according to National Weather Service and private model consensus. Scattered showers and increased cloud cover are expected to limit radiative cooling while advection of marine air suppresses temperatures below seasonal norms of 57–59°F. Market-implied odds reflect this uncertainty, with substantial probability mass on both sub-52°F outcomes from stronger cooling and mid-60s readings if marine influence remains weaker than modeled. Traders are closely watching the next NWS forecast updates and model runs for adjustments to the minimum temperature threshold.