Heat advisory issued for 650,00 people in San Diego County’s valley communities

The roughly 650,000 people who live in San Diego County’s valley communities will be under a heat advisory from 10 a.m. Saturday to 11 a.m. Tuesday due to the arrival of another summer heat wave, the National Weather Service said Friday.

Daytime highs are expected to range from the mid-90s to 102 degrees, and the humidity will drop significantly, adding another level of discomfort.

But the seasonal monsoon will disappear over the weekend, largely removing the threat of lightning, a potential source of wildfires. Thursday’s thunderstorms generated 1,350 cloud-to-cloud and cloud-to-ground lightning bolts.

The weather service has advised drivers that the heat will be even worse in the local deserts, rising as high as 114 degrees in places like Ocotillo Wells and Borrego Springs.

The public can find relief at local beaches, where temperatures will be in the mid-to-upper 70s into Tuesday.

Forecasters say it is possible that Hurricane Carlotta, which was 975 miles south of San Diego late Friday afternoon, could send some cooling moisture into Southern California, and possibly bump up the surf a bit.

Sea surface temperatures will be in the 62-to-70-degree range, which is unusually cool for this time of year.