A weak ridge was forecast to keep the weather fair and mild across San Diego County through Monday, but nights were expected to be chilly, the National Weather Service said.
The onshore flow was predicted to be weak, but persistent, gradually returning a shallow marine layer to coastal areas Sunday night, forecasters said. This could generate some patchy dense fog by Monday morning near the coast.
High temperatures along the coast Sunday were predicted to be from 65 to 70 degrees with overnight lows of 38 to 46. Western valley highs will be 70 to 75, with highs of 66 to 71 near the foothills and overnight lows of 37 to 43.
Mountain highs were expected to be 60 to 67 with overnight lows of 32 to 39. Highs in the deserts will be 74 to 79 with overnight lows of 39 to 48.
On Tuesday, a developing trough was expected to spin up a coastal eddy, deepening the marine layer, and spreading patchy low clouds and cooling well inland through Wednesday.
For the remainder of the week, a strong East Pacific ridge was forecast to funnel disturbances south over the Rockies, forecasters said. This pattern favors fair weather and offshore flow over Southern California, with dry, Santa Ana conditions.
Periods of gusty winds were likely near the coastal foothills at times, along with mild days and chilly nights.
No hazardous marine conditions were expected through Tuesday, but northeast winds were likely to move into parts of the coastal waters Wednesday with gusts to 25 knots possible, the NWS said. There was a small chance these winds could continue at times Thursday and Friday.