Scorching Labor Day Weekend: Excessive Heat, Red Flag Warning, Flex Alert

No monsoonal moisture is expected to accompany this stretch of heat, meaning it will not feel as muggy as recent heat waves, but temperatures will likely reach triple digits across the county

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Click here for a list of county Cool Zones open to the public over the holiday weekend.

A heat wave that will spike temperatures across California 10 to 20 degrees above average over the Labor Day weekend has prompted an excessive heat warning, red flag warning, and an energy conservation alert for San Diego County residents.

The surge of potentially dangerous heat, caused by high pressure strengthening over the Western U.S., will send temperatures soaring into above-average digits starting Friday. The heat wave is expected to last through the holiday weekend with the highest mercury expected on Saturday and Sunday.

Dagmar Midcap's Evening Forecast for September 3, 2020

As the weekend approached, the National Weather Service elevated an excessive heat watch to a warning on Thursday and said triple-digit record heat is possible even in coastal cities like Carlsbad, Encinitas, Chula Vista and San Diego.

The excessive heat warning goes into effect at 10 a.m. Friday through 8 p.m. Monday for western valleys, mountains and the deserts. Coastal areas will be under the same warning from Saturday morning through Monday evening.

“It’s going to be a really hot weekend,” NBC 7's Ashley Matthews said of Friday morning's First Alert Forecast. "Please stay hydrated and stay indoors during those peak hours."

NBC 7's Ashley Matthews shares the First Alert Forecast for the morning of Sept. 4, 2020.
NBC 7's Jackie Crea explains what's in store for our region and how San Diegans are preparing for it.

During the weekend heat wave, residents are urged to use extreme caution and limit their time outdoors, to drink plenty of fluids, check on loved ones, and to never leave children and pets unattended in vehicles.

Temperatures in the deserts could reach 119 on Sunday and Monday, while highs in the western valleys are expected to top out at 102 on Saturday, forecasters said.

Relief won't come at night either. The NWS said it's going to be warm every night this weekend, too.

Red Flag Warning

No monsoonal moisture is expected to accompany this stretch of heat, meaning it will not feel as muggy as recent heat waves.

The dry, hot temps will create risky fire weather conditions.

The NWS on Friday issued a red flag warning to take effect from 10 a.m. Saturday to 6 p.m. Sunday, due to dry, gusty offshore winds with relatively low humidity, according to NBC 7 meteorologist Dagmar Midcap.

The agency had initially issued a fire weather watch for the weekend but canceled it at 10:15 a.m. Friday for the red flag warning instead.

Matthews said Friday the warning will impact San Diego's coastal slopes and foothills, including the communities of El Cajon, Ramona, Alpine, and Escondido.

Flex Alert

Meanwhile, the California Independent System Operator (CAISO) is preparing for an increase in electricity usage due to the heat wave and issued a Flex Alert to urge Californians to limit their energy usage Saturday through Monday from 3 p.m. to 9 p.m. each day.

When California experienced a heat wave like this last month, the state conducted rolling blackouts in order to conserve energy.

A heat wave this holiday weekend will prompt a Flex Alert urging Californians to conserve energy. NBC 7's Nicole Gomez reports.

However, Governor Gavin Newsom signed an emergency proclamation Thursday allowing power plants to ignore certain permit requirements so they can generate more power to help alleviate pressure on the grid.

"Consumers can actively help by shifting energy use to morning and nighttime hours," CAISO said in their alert. "Conservation can lower demand and avoid further actions, including outages, and lessen the duration of possible power interruptions."

CAISO said that it was residents' conservation efforts during the last heat wave that allowed them to avoid rolling outages.

The CAISO offered a series of tips to conserve power, including:

  • Turning off unnecessary lights
  • Using major appliances before 3 p.m. and after 10 p.m.
  • Setting air conditioner thermostats to 78 degrees or higher
  • Using fans and keeping drapes drawn
  • Reducing the use of pool pumps

SDG&E also recommends residents to have flashlights and batteries ready. Those who rely on electric or battery-dependent medical technologies, such as breathing machines, power wheelchairs/scooters, and home oxygen or dialysis, should be prepared to activate their emergency plan.

More energy-saving tips can be found on the FlexAlert website.

Cool Zones

For those who don't have any other way to escape the heat, San Diego County offers several "cool zones," which will utilize social distancing measures to ensure that visitors can stay safe from both the heat and the novel coronavirus.

For a list of cool zones in the county open Monday through Friday, click here.

A limited number of cool zones have been made available to the public over Labor Day weekend. Click here for a list of locations.

Don't let your guard down. It's a warning from San Diego county health leaders urging caution ahead of a historic heat wave during Labor Day weekend. Plus, the CDC wants all 50 states to prepare for vaccine distribution as early as November. NBC 7's Catherine Garcia has the latest headlines for Thursday, September 3rd.

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