The mercury will begin rising in San Diego County on Friday and highs could reach the triple-digits this weekend in many areas.
The National Weather Service office in San Diego said high pressure centered over New Mexico and Arizona will strengthen and expand starting Friday and continuing through Monday.
High temperatures Friday are forecast to reach 74 to 79 near the coast, 83 to 88 inland, 87 to 92 in the western valleys, 95 to 100 near the foothills, 92 to 99 in the mountains and 110 in the deserts.
Triple-digit heat is expected in the western valleys and mountains on Saturday and Sunday, while highs in the county deserts could soar past the 120 mark those two days, forecasters said.
Sunday is expected to be the hottest day of the heat wave, with highs potentially reaching 121 in the deserts, 104 in the mountains and 102 near the foothills of the western valleys.
The weather service issued an excessive heat warning that will be in effect from 10 a.m. Saturday through 8 p.m. Monday in the deserts.
Meteorologists 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.
Slight cooling will arrive in the deserts on Tuesday and continue through at least Wednesday, forecasters said.
Updated at 5:45 p.m., Thursday, July 9, 2020
— From Staff and Wire Reports