LOS ANGELES – Southern California is set to swelter as a heat wave has prompted extreme heat warnings and heat advisories.

Temperatures will hit the triple digits in parts of the Southland starting Wednesday, Aug. 20, with the Woodland Hills neighborhood of Los Angleses in the San Fernando Valley hitting 109 F on Thursday, Aug. 21. – according to a National Weather Service forecast.

"SoCal is on the precipice of the hottest stretch of days so far this summer as the high pressure system over the desert southwest expands westward while at the same time onshore flow weakens," the NWS said in a forecast discussion issued just after 2 p.m. PT Aug. 19.

Extreme heat warnings will be in effect on Thursday, Aug. 21, starting at 11 a.m. PT until Saturday, Aug. 23 at 9 p.m. PT in at least par

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