High pressure over the West Coast continues Friday, with high temperatures Friday afternoon very similar to what was observed Thursday afternoon, the National Weather Service said.
A weak trough was expected to develop over the weekend, increasing onshore flow at the coast and kicking off a cooling trend through the middle of next week.
Coastal areas may begin to cool on Saturday, and inland areas starting Sunday.
Low clouds and fog should increase over the weekend and into the middle of next week. Drier and warmer conditions were expected for the end of the week as offshore flow returns.
Friday along the coast was predicted to be mostly sunny with high temperatures from 79 to 84 degrees. The inland areas were expected to be mostly sunny with highs from 88 to 92. The mountains should be sunny with highs from 79 to 88. The deserts were predicted to be sunny with highs from 95 to 98.
For the valleys, temperatures on Saturday were predicted to be only a couple of degrees cooler than Friday, and a heat advisory has been extended through Saturday for the San Diego valleys, forecasters said.
Cooling was expected to begin to spread into the valleys on Sunday. In addition to the cooling, the weak trough will also draw up some subtropical moisture into Southern California this weekend, bringing some high level clouds.
The cooling trend should really take hold early to mid next week as a fast-moving trough moves across the Pacific Northwest and northern California, the NWS said.
Onshore flow may continue to increase and the marine layer could deepen substantially, with low clouds reaching into the inland valleys each night and morning.
Patchy fog could continue across the outer coastal waters through Friday morning, clearing into the afternoon hours. Patchy fog should occur late nights and mornings through Monday.
— City News Service
