The calendar says fall, but ...

The stores may be stocked with Halloween costumes and the ski runs may be open at Mammoth Mountain, but the weather was anything but fall-like Friday as temperatures soared throughout Southern California.

From the bleachers of Dodger Stadium to the shores of Oxnard, the mercury reached the high 90s and even the low triple digits in some places as a heat wave enveloped the region. And today could be a repeat as forecasters said temperatures wouldn’t begin to dip until Sunday.

The spike in temperatures -- it reached 98 degrees in downtown Los Angeles -- perplexed many Southern Californians because it followed quickly on the heels of a Pacific storm that soaked the region and allowed Mammoth Mountain to open on one of its earliest days ever.

The onslaught of heat was caused by a ridge of high pressure over Nevada and Utah that pushed warm, dry air across Southern California, according to Joe Sirard, a National Weather Service meteorologist. The conditions brought record temperatures to some areas.

It reached 100 degrees in Oxnard; the previous record of 98 was set in 1997. Nearby Camarillo also saw a record reading of 100.

While Phillies fans huddled in 40-degree temperatures back home, Dodgers fans sipped ice drinks, donned sunscreen and viewed the team’s 2-1 victory through their shades. Despite the heat, downtown L.A. still fell six degrees short of its 1958 record for the date.

A couple of hundred miles north at Mammoth Mountain, more than a dozen runs were packed with early-season snow enthusiasts. Sun umbrellas protected skiers and boarders as they munched burgers between runs.

“It was an absolutely gorgeous day,” said Dan Hansen of Mammoth Mountain. “It was one of the earliest openings ever. We got the top of the mountain open.”

Hansen said parking lots began to fill before dawn as 4,500 people descended on the slopes. He said there would be even more snow as temperatures dipped in coming days.

The high pressure will continue to produce high temperatures across the coast and the San Fernando Valley today. Downtown L.A. is expected to chalk up another day in the 90s, as will Pasadena and other parts of the San Gabriel Valley. Forecasters say it will be cooler Sunday through Tuesday.

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