Showers and thunderstorms will be possible Wednesday throughout San Diego County, according to the National Weather Service.
A low pressure system currently hanging over Baja California could produce scattered showers and thunderstorms Wednesday and Thursday, particularly in the mountains and deserts, forecasters said.
The chance of measurable precipitation has been set at 20% today in the county mountains and deserts.
That chance will increase to 50% tonight in both areas, while the western valleys will have a 40% chance and coastal areas will have a 30% chance.
Showers and thunderstorm activity are expected to continue overnight into Thursday, but the system will clear by Thursday night, forecasters said.
Some mountain and desert areas could get up to two-tenths of an inch of rain, but rainfall amounts are not expected to exceed one-tenth of an inch anywhere else in the county today, according to the NWS.
High temperatures today could reach 75 degrees near the coast, 79 inland, 83 in the western valleys, 85 in the mountains and 95 in the deserts.
The system will move east out of the region Friday, but another low pressure system is expected to move in over the weekend, potentially bringing light showers late Friday night through Saturday, forecasters said.