Recent National Weather Service forecasts and ensemble model guidance point to a highest temperature in the upper 70s to low 80s for Seattle on August 13, reflecting a stable late-summer pattern dominated by moderate high pressure and marine air influence from Puget Sound that limits daytime heating. With recent observed highs near 76–78 °F and climatological August averages of 77 °F, traders assign the highest implied probabilities to the 78–81 °F bins because small differences in afternoon cloud cover, wind direction, or marine layer depth can shift the peak by a degree or two. Model consensus remains tight, though minor spread in boundary-layer moisture could allow a brief push toward 82–83 °F if skies clear earlier than expected.