A weak upper low will track southeast off the San Diego County coast Saturday, maintaining a deep marine layer and gusty onshore winds over the mountains and deserts, weather forecasters predicted.
An upper ridge will build into the region beginning Sunday and will dominate the weather through the end of next week, resulting in hotter conditions and drier air, enhancing the fire weather risk, according to the National Weather Service.
High temperatures along the coast Saturday will be 70-75 degrees with overnight lows of 57-62, the NWS said. Inland valley highs will be 76-81 with overnight lows of 51-58.
In the mountains, the highs will be 71-80 with overnight lows of 44- 54. Desert highs will be 92-97 with overnight lows of 62-71.
The marine layer-induced low cloudiness continues Saturday morning and will be slow to dissipate, the NWS said.
"A massive warmup begins tomorrow with the hottest conditions by mid next week, continuing through the end of the week," forecasters said. "Another concern is that dry air will move in west of the mountains on weak east-northeast winds Sunday night-Monday and this dry air doesn't look to budge for a while."
Minimum relative humidity will fall to 10-15% each day inland and will enhance the fire weather risk as fuels are extremely dry.
