clouds and fog
Low clouds in San Diego County. Photo via @palomarskies Twitter

A deep marine layer is expected to persist this week, leading to night and morning low clouds west of the mountains with chances for drizzle each morning, the National Weather Service said.

Wednesday’s high temperatures were expected to be 68 to 72 along the coast, 72 to 77 in the valleys, 71 to 81 in the mountains and 96 to 99 in the deserts, according to NWS.

Another weak closed low pressure system from the southwest was forecast to move inland across the area around Friday. Slow warming is expected through the first half of the weekend across inland areas.

Saturday night temperatures should be near average for the lower deserts and some coastal areas and still around five degrees below average for the inland valleys into the mountains.

The marine layer could still be deep enough for night and morning coastal low clouds to extend inland across most of the valleys.

Temperatures are expected to be cooler Sunday into early next week with the return of stronger onshore flow.