Sunday was expected to be mostly cloudy and cool west of the San Diego County mountains with areas of light rain and drizzle, while the deserts and higher mountains were predicted to be mostly sunny, the National Weather Service said.
The marine layer depth was about 5,000 feet Sunday morning, deep enough for clouds to extend to the Imperial County line along Interstate 8.
Spotty light precipitation in the coastal, valley and foothill area was predicted into Sunday night.
High temperatures along the coast Sunday are predicted to reach 67 degrees, 68 in the western valleys, 68 in the mountains and 89 in the deserts, according to the weather agency.
Skies on Monday were forecast to turn mostly sunny as a building ridge suppresses the marine layer. A stronger ridge was predicted to bring hot days Wednesday through Friday, the NWS said.
Forecasters’ confidence was high that coastal highs will reach the 80s, valley highs will reach the 90s, and the lower deserts will eclipse 100 degrees Wednesday through Friday.
The heat wave was expected to end next weekend when a Pacific trough moves inland across Southern California. This was predicted to be followed by a more substantial West Coast trough that could transition to a much colder pattern with chances of precipitation early next week.
City News Service contributed to this article.