LOS ANGELES (KABC) -- Southern California's big warmup is here, and it's expected to bring triple-digit temperatures to some areas.

The hot temperatures are due to a high-pressure system expanding to Southern California.

The heat is expected to stick around Friday, but temperatures are expected to cool down a few degrees by the weekend.

Los Angeles and Orange counties Friday will see a high of 91 degrees and a low of 63. Temperatures will get back to the mid-80s by the weekend.

The valleys and Inland Empire Thursday will see a high of 98 degrees and a low of 64. Although temperatures will drop, it will still be a hot weekend with highs in the mid-90s.

Beaches Friday can expect morning fog and afternoon sunshine, with a high of 78 and a low of 66 degrees.

The mountains Friday will se

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