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San Diego Weather: Thunderstorms Bring Heavy Showers, Hail, Possible Flash Flooding

By 12 p.m. Friday, some showers and thunderstorms were already touching down in San Diego's mountains and deserts -- and may trickle inland and to the coastline

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The beginning of fall felt more like summer in San Diego County this week. But, on Friday and through the weekend, cooler temps and late afternoon downpours made it feel more like autumn had finally arrived.

NBC 7 meteorologist Sheena Parveen expected the first showers and thunderstorms to hit over San Diego County’s mountains and deserts at around noon, and they showed up right on schedule -- touching down in North San Diego County and in some mountain areas first.

Meteorologist Dagmar Midcap has your First Alert Forecast for Sept. 24, 2021.

By 3:15 p.m., NBC 7's Doppler 7 Radar was detecting thunderstorms producing heavy rain moving west across San Diego County. The heaviest rain fell over Jamul. The rate of precipitation was measured just over one inch per hour, including over the Valley Fire burn scar, the National Weather Service said.

The storm caused damage throughout the county and even forced a rare suspension of play at the Padres game at Petco Park.

The NWS warned of life-threatening flash flooding near creeks and streams, urban areas, highways, streets and underpasses. The potential for flood-related damage is "considerable," the NWS said.

A Flash Flood Warning was issued for parts of San Diego County until 5:30 p.m., including Alpine, Pine ValleyDescanso, Viejas Indian Reservation, Japatul Valley, Skye Valley, Boulder Creek and Captain Grande Indian Reservation. Also under Flash Flood Warning were the areas of Valley Center, Palomar Mountain, Lake Henshaw, Warner Springs, Oak Grove, Aguanga, Santa Ysabel, La Jolla Indian Reservation, Rincon Indian Reservation, Pauma Valley, San Pasqual Indian Reservation, Pauma Indian Reservation, Santa Ysabel Indian Reservation.

A Severe Thunder Storm Warning was also issued for Chula Vista, Escondido and San Diego until 4:15 p.m. The San Diego Fire-Rescue Department advised drivers to slow down and increase their following distance while driving the rain.

By 4:15 p.m., the storm had brought about 1.7 inches of rain to Palomar Mountain and about an inch of rain to Descanso, the NWS reported. The mountains and deserts were expected to get the heaviest rainfall.

Coastal areas saw rain anywhere from a tenth of an inch in Carlsbad to nearly a half-inch in University Heights. In the valleys, Alpine and La Mesa received about a half-inch while Lemon Grove received about .31 inches.

As the band moved towards the coast, it also brought hail. NBC 7 Viewer Kiran Simma shared video of pea-sized hail coming down in their Scripps Ranch backyard in the late afternoon.

The rain also had the potential to reach the coast, too.

“A lot of these could actually start to drift into some of our inland valleys by the afternoon hours and then potentially make their way toward the coast, as they’re weakening,” Parveen explained.

While showers were still possible on Saturday, they were far less likely as the storm system creating the agitated weather pattern was expected to start moving out of the region Saturday, the NWS said.

As for temperatures, Parveen said the coast will be in the mid-70s Friday and inland areas in the mid-80s. Clouds are expected across the county. In the mountains, temps will be in the mid-70s.

The cooler temps will continue through the first weekend of fall in San Diego County.

Parveen said the coast will see highs in the mid-70s Saturday and Sunday, while inland valley communities can expect to stay in the low-80s – a significant drop from the near-triple digit heat that blanketed those areas earlier this week.

“It’s a nice break from the heat,” she added.

Parveen said the temps will remain cool into early next week, too, so if ever there was a time to get into the fall spirit in San Diego, this is it.

Get local First Alert Forecast updates from NBC 7 throughout your weekend here.

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