Seattle’s temperature outlook for August 19 centers on marine moderation typical of the Puget Sound region, where onshore flow and the marine layer cap daytime highs near seasonal averages of 77–78°F. Recent National Weather Service and local model guidance point to mostly sunny or partly cloudy conditions with light winds, supporting the market’s clustering around 76–79°F bins. Minor differences among leading outcomes hinge on the precise strength of the onshore breeze, any diurnal clearing of low clouds, and subtle ridge influence aloft; stronger marine push or lingering stratus would favor the lower end, while reduced cloud cover and slightly warmer 850 hPa temperatures could push readings into the upper 70s. Historical mid-August variability and current dry, stable pattern keep higher bins (80°F+) at lower implied probability.