Temperatures are heating up in Southern California, with triple-digit highs expected through early next week in some areas.

The National Weather Service issued a heat advisory through 8 p.m. Sunday for the San Fernando, San Gabriel and Santa Clarita valleys, and Los Angeles County mountains.

“The extended period of hot temperatures creates a dangerous situation in which heat illnesses are possible, especially for the elderly and people outdoors that do not remain hydrated,” warned the NWS statement. “Temperatures inside vehicles, even if the windows are partially open, can quickly rise to life-threatening levels.”

The weather service advised area residents to “Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors.”

Saturday’s highs reached 88 degrees in downtown Los Angeles, 91 in Glendale, and 104 degrees in Palmdale and Santa Clarita.

More of the same is expected Sunday and Monday before the mercury starts to dip a little as early as Tuesday. Sunday’s highs are expected to reach 87 in downtown Los Angeles and Anaheim, 96 in Pasadena, 97 in Van Nuys and 100 in Valencia.

The beaches will see temperatures in the high 70s until mid-week, then in the low- to mid-70s the rest of the week.

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