Above-normal heat will persist through the week across the Southland, with some valley, mountain and desert areas again facing the possibility of record-setting heat.

The National Weather Service issued a heat advisory that will be in place from 10 a.m. Tuesday until 8 p.m. Wednesday for the Santa Clarita Valley, Santa Monica Mountains Recreational Area, Calabasas, San Fernando Valley, San Gabriel Valley, western San Gabriel Mountains and the 5 and 14 freeway corridors.

Forecasters said daytime temperatures in those areas will range from 95 to 105 degrees, with overnight temperatures in the 60s and 70s, but up to the 80s in the foothills.

“Only minimal relief expected after Wednesday, with a moderate chance of some areas needing an extension to these advisories,” forecasters said.

According to the NWS, a high-pressure system will keep “warmer than normal conditions going through the week and possibly beyond.”

Forecasters also noted that “lingering monsoon moisture” will contribute to a slight chance of isolated thunderstorms in the eastern mountains and deserts of Los Angeles County.

“Breezy onshore winds will continue each afternoon to evening across the interior which combined with the hot and dry conditions will support continued elevated fire weather conditions,” according to the NWS.

The marine layer will continue to keep conditions more mild in coastal areas.

Over the weekend, triple-digit temperatures in Palmdale and Lancaster set new records for July 22, each at 109 degrees—breaking records from 1953 and 2006, respectively.

According to the NWS, excessive heat is the No. 1 cause of weather-related fatalities in the United States.

“Extreme heat will significantly increase the potential for heat-related illnesses, particularly for those working or participating in outdoor activities,” NWS forecasters warned. “Be prepared to drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances.”