The National Weather Service is forecasting hot and unseasonably warm temperatures for inland areas of San Diego County, continuing into early next week.
The excessive heat warning for county deserts and valleys, along with the heat advisory for the mountains, will remain in effect until 8 p.m. Monday.
Closer to the coast, a shallow marine layer will provide some relief, helping moderate temperatures, NWS said.
High temperatures Thursday are expected to reach 75 to 80 near the coast, 83 to 87 inland, 85 to 90 in the western valleys, 94 to 99 near the foothills, 91 to 99 in the mountains and around 110 in the deserts.
By Friday morning, the marine layer is anticipated to deepen, pushing cooling effects into portions of the western valleys.
While temperatures west of the mountains are expected to drop slightly, highs in the mountains and deserts will remain largely unchanged, still reaching levels 10 to 15 degrees above average.
Looking ahead, meteorologists predict the possibility of a low-pressure system near the coast, which could bring additional cooling between Tuesday and Thursday of next week.
