A weak offshore flow and high pressure aloft off the West Coast is expected to bring fair and mild weather to San Diego County Saturday, the National Weather Service said.
Onshore flow will return on Sunday and strengthen into Tuesday, rebuilding the marine layer and spreading low clouds inland nights and mornings, forecasters said.
"The marine layer could get deep enough by midweek and into next weekend for some patchy, light precipitation to develop west of the mountains at times, but at this time the weather forecast is for dry conditions and a slow cooling trend next week," the NWS said.
High temperatures along the coast Saturday were expected to be 65-70 degrees with overnight lows of 42-49, forecasters said. Inland valley highs will be 73-78 with overnight lows of 42-48.
Mountain highs were expected to be 62-69 with overnight lows of 36-43. Desert highs will be 75-80 with overnight lows of 43-53.
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Forecasters expect remaining low clouds to gradually clear by late morning Saturday. Further inland, breezy conditions were ongoing below the passes and near the mountain foothills where gusts of 25 to 35 mph were being reported.
Onshore flow and possibly a weak coastal eddy were expected to return Saturday night into Sunday as a weak short-wave trough digs southeast through the Pacific northwest and weakens the ridge off the West Coast, the NWS said. This will bring minor cooling Sunday, mainly along and west of the mountains. Patchy dense fog is possible near the coast once again Saturday night.
A series of weak troughs moving into California will continue to weaken the ridge through midweek.
"None of these troughs are particularly strong, but could provide just enough lift to squeeze some drizzle out of the deep marine layer, with the best chance on Wednesday," the NWS said. "By Thursday the marine inversion is non-existent, so any low cloud coverage would be patchy."
A weak transitory ridge follows on Thursday for a slight bump up in temperatures, with more troughing and minor cooling Friday and Saturday, forecasters said.
