Cooler weather will linger across San Diego County through Tuesday before a dramatic warm-up later in the week that could bring record-breaking March heat, according to the National Weather Service.
A deepening marine layer will likely bring low clouds and fog to coastal areas and coastal slopes into the morning hours.
High temperatures Tuesday are expected to reach 65 to 68 near the coast, 70 inland, 69 to 72 in the western valleys, 65 to 70 near the foothills, 59 to 67 in the mountains and 80 to 84 in the deserts.
But the cooler stretch will be brief.
A ridge of high pressure over the Pacific is forecast to move into the region beginning Wednesday, pushing temperatures sharply higher. Inland valley highs could climb into the 80s by midweek, with some desert areas nearing 90 degrees.
The warming trend will intensify Thursday and Friday as the high-pressure system strengthens. Temperatures could rise 15 to 25 degrees above normal in some areas, with inland communities possibly approaching or exceeding 100 degrees. Even coastal areas could see highs well into the 80s.
Some inland locations, including Ramona, could challenge or break March temperature records by the end of the week, the NWS said.
The heat may persist into early next week as the ridge of high pressure remains anchored over the region.
