The Los Angeles County Health Department issued a heat advisory for the Antelope, San Fernando, San Gabriel and Santa Clarita valleys and Pomona from Monday through Friday as temps climb up to 110 in some areas.
Similar temps are expected for the Inland Empire. Riverside County officials issued a heat warning for the entire county for the next seven days.
Coastal areas will be cooler with beach temps settling in the 70s.
The jump in daytime temperatures is due to strong high pressure over the Southwest combined with weak onshore flow. It will also get more humid as the week goes on.
Nights will also be warmer than usual during this stretch, with lows ranging from the mid to upper 60s in the valleys to low to mid 70s in the foothills and Antelope Valley.
Officials are reminding the public to drink plenty of water and stay in cool, shaded areas.