Get ready for more oppressively hot weather.

The National Weather Service has issued Excessive Heat Warnings for Southern California beginning Sunday and extending through Wednesday.

On Sunday, temperatures are forecast to reach 100 degrees in the valleys and deserts. A heat warning for Coachella Valley took effect at 11 a.m.

For the greater Los Angeles area, the heat warning takes effect Monday morning. High temperatures are expected to surpass 100 degrees in the San Fernando Valley, San Gabriel Valley, Santa Clarita Valley, and areas of Orange, San Bernardino, and Riverside counties.

Extreme Heat Warning
Excessive Heat Warnings. (NWS)

“Extreme heat will significantly increase the potential for heat-related illnesses, particularly for those working or participating in outdoor activities,” NWS said. “Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.”