Excessive heat warnings have been issued for mountain areas across Southern California through Thursday night, the National Weather Service said.

The weather will remain hot and humid in elevations below 4,000 feet from Santa Barbara County to the Mexican Border in San Diego County, the agency said Tuesday.

The excessive heat index in some areas will be between 100 and 105 degrees. The index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature, according to the Weather Service.

PHOTOS: Heat wave in the Southland

Temperatures at higher elevations will hit the 80s and 90s and could approach record highs, the agency said.

On Tuesday, Lancaster recorded a high of 105 degrees. It was 97 in Woodland Hills, 93 in Pomona and 83 in downtown Los Angeles, according to the Weather Service. In the Inland Empire, Lake Elsinore hit a high of 106 and Ontario reached 97. 

ALSO:

 

Battling a wildfire: 'Nothing sexy about it. It's hard labor'

Jury awards $58 million to man missing part of skull after beating

New member Ratliff is key vote for Vladovic as L.A. board president


Twitter: @LAJourno

robert.lopez@latimes.com