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San Diego’s coast is mild, but the city contains pronounced microclimates. Marine cloud can linger near the ocean in late spring and early summer, while inland valleys become much warmer on the same day. Evenings beside the water often feel cooler than daytime temperatures suggest, so a light layer earns space in a beach bag. Fog, wind and sun exposure can change quickly along cliffs and headlands. Check a neighborhood-level forecast rather than one citywide reading when moving between La Jolla, Downtown and inland parks. Fire weather is a regional seasonal hazard, not a predictable sightseeing feature; follow official alerts when conditions are dry and windy. The practical lesson is to plan layers, water and sun protection even when the forecast looks moderate.