An excessive heat warning for parts of San Diego County will continue through 8 p.m. Sunday, according to the National Weather Service.
Dangerously hot conditions were expected in Borrego Springs and the San Diego deserts, with temperatures up to 116 degrees.
Extreme heat can increase the potential for heat-related illness, particularly for those working outdoors or participating in outdoor activities. The NWS recommends drinking plenty of fluids, staying in air-conditioned rooms and out of the sun, and checking on relatives and neighbors.
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Children and pets should never be left unattended in vehicles for any length of time.
A large area of high pressure over the Southwest was predicted to maintain hot summer weather inland, and a monsoonal, southeast flow over Southern California, the NWS said.
Isolated thunderstorms could occur in the higher mountains and deserts Saturday afternoon, but could be more widespread Sunday and Monday as weak disturbances from the southeast track farther north and west, forecasters said.
High temperatures along the coast Saturday were predicted to be 71 to 76 degrees with overnight lows of 62 to 67. Highs in the western valleys were expected to be 82 to 87, and 93 to 98 near the foothills with overnight lows of 64 to 71. Highs in the mountains were expected to be 93 to 101 with overnight lows of 67 to 76, and highs in the deserts were predicted to be 113 to 118 with overnight lows of 85 to 92.
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"It's looking like a cooler and drier trend next week with temperatures back to normal by Tuesday for coast to mountains, remaining a little above normal in the deserts," forecasters said.
A southwest swell from 200-220 degrees at 16 seconds could bring elevated surf to San Diego County beaches this weekend. Surf of 3 to 6 feet was expected, with a high risk of rip currents. A beach hazards statement was in effect through Sunday evening.