The National Weather Service issued a flash flood watch for the San Diego County mountains from Tuesday afternoon through Wednesday evening as forecasts showed thunderstorms developing in the afternoons.
The weather service warned of “very heavy rainfall rates well in excess of one inch per hour, and one-half inch in 15 minutes” that could flash flooding in normally dry washes and poorly drained areas.
The warning is confined to the mountains, but forecasters said there is a good chance of isolated thunderstorms in the western valleys and eastern deserts.
Temperatures on Tuesday are forecast to be 73 to 78 near the coast, 79 to 84 inland, 82 to 87 in the western valleys, 89 to 94 near the foothills, 86 to 93 in the mountains and 102 to 107 in the deserts.
Forecasters said the region will warm up and dry out beginning on Thursday and continuing through Saturday.