Temperatures in inland San Diego County will begin rising Thursday and could climb past the 115-degree mark in certain areas in the coming days.
A National Weather Service excessive heat warning for the deserts is set to take effect at 11 a.m. Friday morning and extend until 9 p.m. Saturday. A less severe heat advisory for the mountains and valleys will run concurrently.
"Strengthening high pressure aloft over the Desert Southwest will bring hot weather inland Friday and Saturday," according to the weather service.
High temperatures in the forecast for inland coastal areas are 82 to 87 degrees Thursday, 86 to 91 degrees Friday and 88 to 93 degrees Saturday. Highs of 86 to 91 degrees in the western valleys and 93 to 98 degrees near the foothills Thursday will rise respectively to 90 to 95 degrees and 97 to 102 degrees Friday and to 92 to 97 degrees and 98 to 103 degrees Saturday.
Predicted highs for the mountains are 91 to 99 degrees Thursday, and 94 to 102 degrees both Friday and Saturday. In the deserts, highs of 109 to 114 are expected Thursday, and high temperatures will range from 113 to 118 degrees both Friday and Saturday.
In the mountains, the heat and isolated thunderstorms will also increase the risk of dry lightning, which can spark wildfires.
"Hot and dry conditions near the surface accompanied by gusty southwest to west winds on the desert mountain slopes each afternoon and evening will increase fire weather concerns, especially on Friday and Saturday," according to the weather service,
The hot weather will raise the risk of heat-related illness and anyone working or spending time outdoors would be more susceptible, as will the elderly, children and those unaccustomed to the heat. Forecasters advised residents to reschedule strenuous activities to early morning or evening, drink plenty of water, wear lightweight and loose fitting clothing and be aware of the signs and symptoms of heat exhaustion and heat stroke.
Authorities have also warned against leaving children, seniors or pets in parked cars, which can heat up to lethal levels in just minutes, even with a window partially open.
