Websan diego weather forecasts. Weba few to around 5 degrees cooler than monday, 10 to 15 degrees above average for portions of the mountains, deserts, and inland valleys. Weba few to around 5 degrees cooler than monday, 10 to 15 degrees above average for portions of the mountains, deserts, and inland valleys. High temperatures for tuesday for the coast and valleys from the lower to mid 70s near the coast to the 90s for the inland valleys, for the apple and lucerne valley in the upper 80s to mid 90s, in the lower. Excessive heat warnings in effect through 8 pm monday for the low deserts, inland empire, san diego valleys, and santa ana mountains. Heat advisories in effect through 8 pm monday for the mountains in san diego, riverside, and san bernardino counties. Otherwise, mostly cloudy, with a low around 63. North wind around 5 mph. Patchy fog before 8am.
