San Diego County will see relatively calm weather with mild temperatures before a weekend warming trend, according to the National Weather Service.
The marine layer will thicken overnight, bringing low clouds and fog into inland valleys Tuesday.
Forecasters anticipate minor daily temperature changes through Thursday, with persistent night and morning low clouds along the coast and western valleys.
High temperatures Tuesday are expected to reach 64 to 69 along the coast, 68 to 73 in the western valleys, 61 to 68 in the mountains and around 80 in the deserts, the NWS said.
A significant warming trend is on the horizon, with temperatures climbing sharply from Friday into early next week.
By Sunday and Monday, inland valleys and mountain areas could see highs soaring 10 to 15 degrees above average.