A view of the Anza-Borrego Desert from Mount Laguna in the Cleveland National Forest. Photo by Michael Romanov via Wikimedia Commons

A heat wave will bring blazing temperatures to the San Diego County mountains and deserts this weekend, according to the National Weather Service.

A strong high-pressure system over the Great Basin will continue to expand westward, ushering in the sweltering conditions through Monday in most of the county, forecasters said.

The weather service issued an excessive heat warning that will be in effect from 9 a.m. Saturday to 8 p.m. Monday in the deserts. A heat advisory is also in effect until 8 p.m. Monday in the mountains.

Highs in the deserts could reach 120 on Saturday and 118 on Sunday, while the mercury in the mountains is expected to reach 102 on Saturday and 101 on Sunday, according to the weather service.

At the height of the hot spell, lows temperatures in the deserts will likely drop no further than the upper 80s to low 90s, making for minimal relief even at night, forecasters advised.

Meanwhile, high temperatures on Friday are expected to be in the low 70s to low 80s in coastal areas, the low to mid 80s in the western valleys, the low to mid 90s near the foothills, the low 90s to low 100s in the mountains and the low to mid 110s in the deserts.

The weather service said the extreme heat will significantly increase the potential for heat-related illnesses, particularly for those working or participating in outdoor activities.

People should be prepared to drink plenty of fluids, stay in an air-conditioned room, stay out of the sun and check up on relatives and neighbors.

While young children and pets should never be left unattended in vehicles under any circumstances, it is much more imperative to avoid doing so during such oppressive conditions, amid which car interiors can reach lethal temperatures in a matter of minutes, officials noted.

To help residents beat the heat, San Diego County has opened public “Cool Zone” locations in Alpine, Borrego Springs, Fallbrook, Lakeside, Potrero, Ramona, Santa Ysabel, Spring Valley and Valley Center.

The list of locations can be found at San Diego County’s website

The spate of torrid weather is expected to peak Saturday and Sunday, then slowly diminish into the middle of next week, by which time temperatures should be at or near normal levels across San Diego County, forecasters said.

Updated 7:40 p.m. July 9, 2021

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