Temperatures will begin to cool Thursday in the San Diego County deserts, but highs are still expected to reach the triple digits through Friday, according to the National Weather Service.
A trough of low pressure will continue moving into southern California Thursday, bringing slightly cooler temperatures in the mountains and deserts until Sunday, forecasters said.
Highs in the deserts are forecast to reach 103 Thursday and 102 on Friday, then dip to 97 on Saturday.
An excessive heat warning that will last until 9 p.m. Thursday in desert areas.
Nighttime lows are expected to remain in the low-70s through tonight in the county deserts, meaning the minimal cooling at night could pose a health risk to those who don't have access to air conditioning because the body needs time to cool down from the day's heat, according to the NWS.
The combination of hot days and warm nights is expected to increase the threat of heat illness, and the NWS urged residents to drink plenty of fluids, stay out of the sun and check up on relatives and neighbors.
High temperatures elsewhere Thursday could reach 71 degrees near the coast, 76 inland, 81 in the western valleys and 85 in the mountains.
Winds out of the west will be moderate Thursday, with wind speeds expected between 15-20 mph and gusts possibly reaching 30 mph in the deserts tonight.
Conditions will continue cooling through Saturday, then high pressure will return and cause temperatures to rise above average again on Tuesday and Wednesday, forecasters said.
