An excessive heat warning goes into effect Sunday morning as temperatures continue to rise across the Southland, creating an "elevated fire danger" that will extend into next week, according to forecasters.
The advisory will be in place from 10 a.m. Sunday through 10 p.m. Wednesday amid triple digt temperatures in some areas, especially the San Fernando Valley.
The peak of the heat wave is expected to occur Monday, when highs are predicted to reach 97 degrees in Downtown L.A.; 103 in Pasadena and Burbank; 104 in San Gabriel; 106 in Fullerton and Yorba Linda; 107 in Saugus and Lancaster; and 109 in Woodland Hills.
Temperatures should be 10 to 20 degrees above average Monday, said National Weather Service meteorologist Robbie Munroe.
The weather service attributed the heat wave to a "strong upper-level high-pressure system over the region combined with weakening onshore flow."
A statement added that triple-digit heat will be possible across Valley areas, the mountains and at lower elevations and the deserts.
The NWS said it is certain that even coastal areas "will also warm significantly during this heat wave, with highs mostly in the 80s near the beaches and between 90 and 100 across inland portions of the coastal plain, including Downtown Los Angeles."
The heat wave will also bring warm overnight temperatures, the statement said, adding there is a potential for "significant heat impacts across much of southwest California" for residents without air conditioning.
Additionally, "the hot and dry conditions combined with very dry fuels" -- the vegetation -- "will bring an extended period of elevated fire danger to southwest California."
Forecasters urged residents to protect themselves and those close to them by finding access to air conditioning, reducing time spent outdoors, drinking plenty of water, checking on friends and neighbors -- especially the elderly -- and by never leaving children, seniors or pets in parked cars, even with windows cracked open. The interior of a vehicle parked in hot weather can rapidly reach lethal levels.