SAN DIEGO -- Temperatures could reach triple digits in portions of the inland valleys Wednesday and extreme heat will blanket desert areas until cooler weather arrives heading into this weekend, according to the National Weather Service.
A high pressure system currently over northwest Mexico will make its way further west Wednesday, bringing extreme heat and dry conditions over the next two days, NWS meteorologist Stefanie Sullivan said.
The NWS issued an excessive heat warning that will last from 11 a.m. Wednesday through 9 p.m. Thursday for desert areas.
A heat advisory will also be in effect during that same time period for the inland valleys, including El Cajon, Santee and Escondido.
The mercury could climb to 116 degrees in the deserts on Wednesday and Thursday, forecasters said. Temperatures in the inland valleys will be in the low 90s both days and could reach triple digits near the foothills.
The NWS advised that those who work outdoors should avoid the midday sun, wear light, loose-fitting clothing and drink plenty of water.
Nighttime lows are expected to remain in the low 80s through Thursday night in the 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.
The NWS also urged residents to drink plenty of fluids, stay out of the sun and check up on relatives and neighbors.
High temperatures Wednesday could reach 79 degrees near the coast, 88 inland, 92 in the western valleys, 101 near the foothills, 99 in the mountains and 116 in the deserts.
A trough of low pressure will make its way inland on Friday, causing temperatures to drop to around average throughout the weekend, Sullivan said.