The Southland will bake on the sixth day of a heat wave today and remain under the threat of wildfire as high surf continues to batter the coast.
A red flag warning denoting a risk of what National Weather Service forecasters call “explosive fire growth” was in effect today in the mountains and foothills of Los Angeles, Ventura and Santa Barbara counties and due to expire at 9 tonight.
The red flag zone includes the vast and potentially fire-prone Angeles National Forest in Los Angeles County and the Ventura and Santa Barbara county portions of the adjoining Los Padres National Forest.
Any fire ignition will have the potential to explode over the mountains “due to hot temperatures, low humidities, relatively light winds, instability and extremely dry fuels,” according to an NWS statement. “If fire ignition occurs, there could be rapid spread of wildfire that would lead to a threat of life and property.”
The humidity level was between 12 and 20 percent Monday and expected to be a bit higher today, forecasters said.
Also confronting the region today was what an NWS statement called “dangerously hot weather,” which prompted the weather service to issue an excessive heat warning that will be in effect until 7 tonight in the San Gabriel, San Fernando and Santa Clarita valleys and the Santa Monica Mountains Recreational Area in Los Angeles County and parts of Ventura County.
A less serious heat advisory will be in force in Orange County until that time.
Forecasters said heat index values — how hot it really feels, due to the humidity — will be between 100 and 110 degrees in the valleys of Los Angeles and Ventura counties today.
“The combination of heat and humidity will create a dangerous situation in which heat illnesses are possible, especially for the elderly and youth,” an NWS statement said. “Never, ever leave people or pets in enclosed vehicles, even for a short period of time with the windows cracked open.”
The heat prompted Los Angeles Department of Water and Power customers to set a record for peak energy demand Monday — 6,196 megawatts, the department announced.
The previous record was 6,177 megawatts set on Sept. 27, 2010. The peak demand was nearly double the amount of energy demand experienced on a typical day in Los Angeles, according to General Manager Marcie Edwards.
Another record is expected for today, he said.
The DWP is urging customers to save energy wherever possible, including by not using large appliances today.
Along the coast, a “high rip current risk” and “dangerous swimming conditions” will prevail today, according to the NWS, which forecast surf of between 2 and 4 feet and maximum sets of 5 feet. The surf will lessen Wednesday.
The heat wave began Thursday. Temperatures are expected to start climbing down Wednesday.
The NWS forecast highs today of 84 in San Clemente and Newport Beach; 88 in Avalon and at LAX; 95 on Mount Wilson; 100 in Long Beach, Anaheim and downtown L.A.; 91 in Laguna Beach; 98 in Irvine; 101 in Yorba Linda and Mission Viejo; 102 in Fullerton, Palmdale, Lancaster and San Gabriel; 105 in Pasadena and Burbank; 108 in Saugus; and 109 in Woodland Hills.
The forecast calls for temperatures to go down Wednesday by several degrees and again on Thursday. Downtown L.A., for example, is forecast to go from a high of 100 today to 91 Wednesday and 83 on Thursday, staying at roughly that level for several days.