Worst of Southern California heat wave and smog hit Saturday

The worst of a weekend heat wave is forecast to hit Southern California this weekend.

Here is what you need to know:

Forecast

The heat is expected to peak Saturday as a high-pressure zone extends from the Southwest and lingers over the region, the National Weather Service said. Temperatures should start to cool by Monday, when a trough of low pressure is forecast to move into the area.

Heat advisory

Officials have issued a heat advisory for most of the Los Angeles County valleys and mountains, as well as the Inland Empire, where triple-digit temperatures are forecast through the weekend.

The advisory is in effect through Sunday for the Santa Clarita, San Fernando and San Gabriel valleys, with temperatures forecast to hit 95 to 103 degrees. Temperatures could reach 104 degrees across lower elevations in the mountains.

In the San Bernardino and Riverside county valleys, a heat advisory is in effect through Monday. High temperatures there are expected to range from 98 to 105 degrees.

Beating heat

Residents are advised to hydrate, wear lightweight, loose-fitting clothing and stay indoors between 10 a.m. and 3 p.m., when the sun is strongest. Los Angeles County will be operating cooling centers and has compiled a list of public pools and splash pads.

Poor air quality

Air quality officials also issued an ozone advisory for the South Coast Air Basin through Tuesday morning, saying that the heat will combine with atmospheric inversions to trap smog pollution close to the ground.