National Weather Service forecasts and supporting model consensus point to a daytime high in the mid-to-upper 70s for Seattle on August 10, shaped by persistent onshore flow from the Pacific that maintains marine-layer influence and limits afternoon heating. This setup creates tight differentiation between the leading 76–77°F and 78–79°F outcomes, as small shifts in cloud timing, boundary-layer mixing, or sea-breeze strength can alter peak readings by 1–2°F. Recent days have shown gradual cooling from upper-80s readings earlier in the week, consistent with climatological August averages near 76–79°F and the absence of strong offshore warming. Traders weigh these variables against ensemble spread ahead of final observations.