SAN DIEGO -- Temperatures will continue heating up Thursday in San Diego County and sweltering heat is expected in the deserts over Labor Day Weekend.
High pressure will continue to build over the southwest Thursday, then center itself over the Four Corners region this weekend and usher in monsoonal moisture through Wednesday, forecasters said.
The National Weather Service issued an excessive heat watch that will be in effect from Friday morning through Saturday evening in the county deserts.
The mercury in the deserts could reach 113 on Friday and 114 on Saturday before dropping to 112 on Sunday, then 103 on Monday, forecasters said. Highs in the inland valleys will reach 90 on Sunday before cooling off slightly early next week, while temperatures near the foothills are expected to peak at 98 on Sunday.
Thunderstorms will be possible in the county mountains each afternoon from Sunday through Wednesday and inland valley areas could see thunderstorm activity Monday afternoon.
The county deserts will have a chance of thunderstorms each afternoon from Monday through Wednesday.
High temperatures Thursday could reach 83 degrees near the coast and inland, 87 in the western valleys, 94 near the foothills, 95 in the mountains and 110 in the deserts.
Nighttime lows could remain in the low 80s throughout the weekend 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, 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.