Temperatures in Beverly Hills, Bel Air and Holmby Hills could hit triple digits starting Friday, Oct. 2, as the longest heat wave of the season settles over Southern California.

The National Weather Service issued an extreme heat watch covering Los Angeles County, including the Platinum Triangle, from Friday morning through at least Thursday, Oct. 8. NWS Los Angeles posted the alert on Wednesday, Sept. 30, warning the event could stretch even longer.

Saturday, Oct. 3, is expected to be the peak day. Downtown Los Angeles and Pasadena are forecast to reach 100 degrees, with temperatures across the L.A. basin running 10 to 15 degrees above normal through next week, NBC Los Angeles reported. October highs in downtown L.A. typically average 75 to 80 degrees.

NWS meteorologist Ryan Kittell told LAist that previous heat waves this season were hotter but shorter. "Unfortunately, we don't really see an end to it as far as we can tell …" Kittell said.

NWS Oxnard meteorologist Rose Schoenfeld told the Los Angeles Times the heat wave is being driven by high pressure and a lack of wind. Weather service models indicate it could last through mid-October.

Heat raises wildfire risk in the canyons

The heat also raises fire concerns for Bel Air and Holmby Hills canyon residents. Humidity levels are expected to stay low throughout the event.

The risk remains high.

Kittell said conditions likely will not reach the threshold for a red flag warning but cautioned that a fire starting in the wrong area could grow quickly. The region has a history of large fires in similar conditions at this time of year, he said.

Southern California Edison (SCE) said Thursday, Oct. 1, that nearly 10,000 customers in parts of Riverside County were under consideration for preventive Public Safety Power Shutoffs. As of Oct. 1, SCE's announcements did not include any Beverly Hills, Bel Air or Holmby Hills circuits.

How to stay safe

The NWS advises residents to drink plenty of fluids, stay in air-conditioned spaces, avoid direct sun and check on neighbors and relatives. Children and pets should never be left in unattended vehicles. Car interiors can reach lethal temperatures within minutes.

Los Angeles County residents can call 3-1-1 for a list of cooling centers. City of Los Angeles recreation centers, senior centers and libraries are also available as cooling options.