Heat alerts warning of dangerous weather conditions are in effect for each of San Diego County’s climate zones through Thursday as a stifling heat wave peaks.
The heat warning has been extended through Thursday evening for San Diego’s coasts and inland valleys, where dangerously high temperatures could be as much as 10-15 degrees above average.
Inland temperatures reached triple digits again on Wednesday, while coastal temperatures reached 90s, according to NBC 7 Meteorologist Greg Bledsoe.
Mark MullenMark Mullen
A sign warning hikers to be cautious amid an extreme heat warning was posted at San Dieguito Park Trail in Rancho Santa Fe on Sept. 9, 2026. (Mark Mullen)
Gillespie Field airport in El Cajon unofficially hit 108 degrees just a little before 1 p.m. Wednesday, Bledsoe said.
San Diego County’s mountains are under a heat advisory through Thursday at 8 p.m. Showers are still possible over the mountains each afternoon, but chances will drop as the week goes on.
Out in the boiling desert, an extreme heat warning is in effect through Friday at 8 p.m.
The weekend will continue to cool. We should also see more morning marine layer clouds, and cooler overnight temperatures. More seasonal temperatures will continue into next week.
Adding to the discomfort is excessively high humidity stemming from a mix of monsoonal moisture and heat rising from warmer-than-usual ocean temperatures, according to the National Weather Service. Much of the county continues to feel muggy and the mountains saw some afternoon thunderstorms this week.
Tropical storms hundreds of miles away, like the recent Hurricane Marie, can also increase humidity.
“The effects of Marie have faded but the monsoonal flow has returned. So, we’re not really getting much of a break from the humidity,” Bledsoe said.
While some relief will come Thursday and Friday, lower humidity and cooler temperatures are not likely to come before next Sunday, according to the NWS.
SDG&E power outages
The extreme heat also prompted San Diego Gas & Electric to carry out some unplanned outages across the county.
Within 24 hours between Tuesday and Wednesday, SDG&E had 29 unplanned outages.
A blackout struck at about 1:30 p.m. Wednesday, knocking out power to 8,719 SDG&E customers in Del Dios, Green Valley, the Lake Hodges vicinity, Poway, Rancho Bernardo, Rancho Penasquitos and San Pasqual, according to the utility.
Service was expected to be restored to the affected areas by late afternoon.
“Community members out there with this type of temperature, they’re going to start using the A/C a little bit more, fans, and that on top of appliances that they already use. That’s going to put strain on the grid,” SDG&E spokesperson Humberto Gurmilan said.
Until then, SDG&E recommends conserving energy by minimizing the use of appliances during peak hours. If you are impacted by a power outage, SDG&E recommends visiting their website to get updates on restoration.
Hottest first pitch ever at Petco Park
Wednesday’s temperatures broke the record of the hottest first pitch ever at Petco Park in downtown San Diego, according to the Padres baseball team.
Despite the extreme temperatures, the Friar Faithful still showed up in droves to support their team.
It was the hottest Padres game ever in Petco Park history. NBC 7’s Jeanette Quezada has more on how fans tried to stay cool during the game.
Cooling off during the heat
The NWS issues these warnings because heat illnesses increase during periods of extreme heat. Residents are urged to drink plenty of fluids, stay in air-conditioned rooms and stay out of the sun.
San Diego County released tips and advisories on avoiding heat-related illnesses here.
Never leave pets or children unattended in vehicles. “Car interiors will reach lethal temperatures in a matter of minutes,” the NWS said.
Dozens of locations across San Diego County act as “Cool Zones,” providing a space where residents can seek relief from the heat for free. See the list here.
San Diegans and tourists packed local beaches this Labor Day to escape the sweltering heat and muggy conditions, reports NBC 7’s Todd Strain.