National Weather Service and ensemble model guidance place Seattle’s August 25 high near 82–84 °F, aligning with the market’s tight clustering around the 82–83 °F and 84–85 °F bins. Persistent onshore flow and a shallow marine layer are expected to cap daytime heating several degrees below the 77 °F August normal at Sea-Tac, while limited afternoon clearing and light northwesterly winds prevent stronger offshore ridging that could push readings into the upper 80s. Recent upper-level trough passage has kept the pattern moderate, with little spread among guidance solutions. Traders therefore assign the highest implied probabilities to the narrow mid-80s window, though any earlier marine-layer dissipation could shift the outcome modestly higher before sunset.