National Weather Service forecasts call for a high near 69°F in Seattle on June 30 under a marine layer with morning clouds giving way to partial afternoon sun. A broad upper-level trough offshore sustains onshore flow and stratus, capping daytime heating several degrees below the late-June normal of 73–74°F. Model consensus highlights modest variability in cloud timing and boundary-layer mixing, which directly separates the tightly bunched 66–67°F and 68–69°F bins from lower or higher outcomes. Historical analogs show similar trough patterns rarely allow Seattle to reach 72°F without stronger ridging. Updated model runs and morning soundings ahead of the close will refine whether limited solar insolation pushes readings into the upper 60s or holds them mid-60s.