Temperatures will continue climbing across inland portions of San Diego County Tuesday as forecasters warned that the hottest weather of the week remains ahead.
While coastal communities will largely avoid the worst of the heat, inland valleys, mountains and deserts are expected to warm steadily as high pressure strengthens over the Southwest, according to the National Weather Service.
An extreme heat warning will take effect Wednesday morning for the county's valleys and mountains and remain in effect through Thursday evening. A heat advisory will also be issued for coastal areas during the same period.
Forecasters said Wednesday is expected to be the hottest day of the week, with temperatures reaching well into the 90s in the mountains and inland valleys while climbing into the triple digits in the deserts.
Low temperatures will offer little relief, remaining in the 70s overnight in many inland communities.
"Vulnerable populations and those who are outside for long periods will have a greater chance to see heat impacts and related illnesses," the weather service said.
Monsoonal moisture is expected to decrease through midweek as the high- pressure system expands over Southern California, reducing but not eliminating the possibility of mountain storms.
Forecasters said there remains a slight chance of afternoon and evening showers and thunderstorms over the mountains through the middle of the week.
The National Weather Service also warned that astronomical high tides combined with a south swell could continue producing minor coastal flooding in low-lying areas, beach parking lots and boardwalks during evening high tides through Tuesday night.
An elevated risk of rip currents is expected to continue through Wednesday.
Temperatures are expected to ease by Friday and into the weekend as the ridge of high pressure weakens and onshore flow strengthens, forecasters said. Humidity is expected to linger, however, and monsoonal storm chances could increase again late in the week.
