A hot air mass developing over Southern California will send valley and mountain temperatures climbing into triple digits today, but the above-normal heat will begin dissipating within a couple of days, forecasters said.
The humidity also will be relatively high today, but the heat index values that gauge how hot the weather really feels "are expected to remain below dangerous thresholds," and there are no predictions of showers and thunderstorms in the forecast, according to a National Weather Service advisory.
Still, it will be warm and muggy, with temperatures running roughly 7-9 degrees above normal, said NWS meteorologist Curt Kaplan, who added that temperatures would be closer to normal by Thursday, making the current hot spell something less than a heat wave.
"A hot air mass will continue to develop over Southern California as a high-pressure system expands west over the region," according to the NWS advisory.
"Triple-digit high temperatures will be common in the warmest inland locations" today, including the western San Fernando Valley, eastern San Gabriel Valley and foothills, and the Santa Clarita Valley, it said. "The only escape from the heat will remain at the beaches."
Glendora is expected to reach a high of 102 degrees, Diamond Bar 101, and Claremont 105, according to the National Weather Service.
The NWS forecast highs of 103 in the San Gabriel, San Fernando, Santa Clarita and Antelope valleys and the San Gabriel mountains at lower elevations. Highs will be lower Wednesday and even lower Thursday, according to forecasters.
The NWS forecast highs today of 79 in Newport Beach; 82 in Avalon and at LAX; 89 on Mount Wilson; 92 in downtown L.A.; 94 in Long Beach; 96 in San Gabriel; 97 in Anaheim; 99 in Burbank and Pasadena; 102 in Palmdale; 103 in Saugus, Lancaster and Woodland Hills. The high in Woodland Hills normally would be around 94 at this time of the year, Kaplan said.