A low pressure system that extends from the West Coast to the continental divide will produce a 4,000-foot-deep marine layer on Friday that’s likely to spread across all of San Diego County, the National Weather Service said.
That’s more than twice as deep as the marine layers that typically form this time of year, and many of those clouds typically stay largely at or near the coast. Monday’s marine layer in San Diego was 3,000 feet deep.
Friday’s daytime high will reach 78 degrees in San Diego, which is about average for early September. But forecasters say the region will turn cooler during the weekend, a shift that’s expected to last until the middle of next week. Temperatures will be 4 to 7 degrees below average in many places.
The moisture from Thursday’s marine layer helped limit the growth of the Airport fire in Orange and Riverside counties. That blaze has burned more than 23,000 acres. Forecasters said that wind currents will prevent smoke from the fire from drifting over San Diego County.
