Været i Half Moon Bay i juli

San Francisco-forum threads on July fog are consistent: this is the deepest fog season of the year, especially near the water, and the pattern is for it to clear downtown and most neighborhoods by late morning before rolling back in during late afternoon - though how much any given day burns off depends entirely on which part of the city you're in. Posters are firm that this isn't something to plan around avoiding; it's part of what the city is in summer, and it doesn't stop sightseeing. The advice is uniform: long pants and a jacket, dressed in layers. The record explains why the fog wins: 19.1C days, 12.6C nights, essentially no precipitation across the whole month, and a 14.8C sea - San Francisco's summer is dry, cool and grey rather than the postcard version most visitors expect.