The mercury could soar to 112 again Thursday in the San Diego County deserts, but cooler weather will arrive on Friday, according to the National Weather Service.
The high pressure that has caused sweltering conditions since Tuesday will be replaced by a low-pressure system, which will also bring a slight chance of rain Friday night through Saturday morning everywhere except the deserts, forecasters said.
High temperatures Thursday are forecast to reach 75 degrees near the coast, 81 inland, 83 in the western valleys, 88 near the foothills, 93 in the mountains and 112 in the deserts.
An excessive heat warning will last until 7 p.m. Thursday in the deserts.
NWS officials urged residents to drink plenty of fluids, stay out of the sun and check up on relatives and neighbors. Also, young children, senior and pets should be never be left unattended in a vehicle parked during the day, with car interiors able to reach lethal temperatures in minutes.
Highs in the deserts will drop to 100 on Friday, while temperatures in the western valleys will reach the low-to mid-70s, forecasters said.
