Temperatures are heating up in Southern California, with near-triple-digit highs Sunday and Monday 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 advisories for the San Fernando and San Gabriel valleys were canceled early Sunday.

“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.”

Sunday’s highs were expected to reach 87 in downtown Los Angeles and Anaheim, 93 in Pasadena and Van Nuys, 100 in Valencia and Lancaster and 99 in Palmdale.

More of the same is expected Monday before the mercury starts to dip a little on Tuesday and a little more on Wednesday.

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

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