**Persistent marine layer cloudiness and limited solar heating are the main drivers keeping Seattle's June 28 high temperature forecast centered in the mid-to-upper 60s.** National Weather Service guidance currently projects a mostly cloudy day with a high near 68°F, while other models and services range from 64–68°F amid south winds of 5–8 mph. Seattle’s coastal location and Puget Sound influence typically suppress daytime maxima in late June relative to inland areas, and recent forecasts show no strong high-pressure ridging to clear skies or boost temperatures. This narrow expected range explains the tight market clustering around 64–69°F outcomes, with traders weighing minor differences in model timing of any sun breaks or cloud persistence that could shift the daily maximum by a degree or two. Updated NWS and model runs over the next 24 hours will provide the clearest signals ahead of resolution.