Weakening high pressure over the Southwest was forecast to bring cooling to San Diego County Saturday through Sunday, while onshore flow maintains a marine layer and clouds west of the mountains, the National Weather Service said.
High temperatures in coastal areas Saturday were expected to be 67-72 degrees with overnight lows of 54-60, the NWS said. Western valley highs will be 74-79 and 80-85 in the foothills with overnight lows of 51-56.
Mountain highs were expected to be 79-89 with overnight lows of 50-58. Highs in the deserts will be 105-110 with overnight lows of 67-76.
On Monday, an upper-level disturbance was expected to bring scattered high clouds and further cooling, the NWS said. The greatest precipitation potential was forecast to be light rain or drizzle Monday and Tuesday mornings west of the mountains as a trough deepens the marine layer to between 3,000 and 4,000 feet.
The cooling trend was predicted to continue Tuesday and Wednesday, the NWS said. Along with the cooling, forecasters predicted moderate to strong afternoon and evening winds in the mountains and deserts.
Cooling will weaken the inversion for better afternoon clearing of the morning stratus in the coastal and western valley zones. The trough lifts north Thursday and Friday for minor warming late next week.