Storm Supplies a July Surprise : Weather: Rare summer rain slickens streets, contributes to six-car crash in Downtown L.A. Lightning knocks out electricity briefly in Orange County.

Rare summer squalls doused much of Southern California on Sunday, soaking beach-goers and baseball fans alike with an unseasonal drizzle and leaving some roads dangerously slick.

Forecasters said the rainy weather will probably continue today and Tuesday, but predicted that any showers would be light. Sunday’s rainfall only reached halfway to the June 16 precipitation record for Los Angeles, 0.04 inches, set in 1914. On Sunday, 0.02 inches of rain fell in the Civic Center.

Scattered showers were reported from Santa Monica to San Bernardino, and lightning storms momentarily cut off electricity to about 15,000 homes in Orange County. Rain also made for slippery driving conditions in Downtown Los Angeles, contributing to a six-car crash on a transition road between the San Bernardino and Santa Ana freeways. No injuries were reported.

Los Angeles County Department of Health Services officials warned beach-goers that the rain could increase bacterial levels in the ocean and urged swimmers to avoid water near storm drains.

In the language of weather, the strange storm was the result of “an upper level disturbance with convective showers,” said Curtis Brach, a meteorologist with WeatherData Inc., which provides forecasts for The Times.

The weather pattern is normal for July and August over parts of the Southwest, especially the desert, Brach noted, where a high pressure area sets up and then kicks off the “monsoonal” season, pulling up moisture from northern Baja California and the Pacific Ocean and dumping it in the desert and Arizona.

This time, the system “just drifted westward,” Brach said. “This is fairly unusual.”

Of course, the wet weather dampening Southern California was far less troublesome than the killer heat wave scorching the Midwest, where more than 200 people have died from heat-related conditions, and the East Coast.

Indeed, the rain seemed as much a help as a hindrance for a lucky few. At the Federation Internationale De Volleyball tournament in Hermosa Beach, observers said moisture might actually aid the players.

“It’s probably a lot easier playing on the packed sand with more traction, and it’s also a little cooler,” said Cris Bennett, owner of Good Stuff on the Strand restaurant, a surf-side eatery with a view of the tournament. “But looking up for a spike or a set, you have to get rain in your eyes.”

Bennett, who despite the weather reported a 30-minute wait for tables at his restaurant, said some beach-goers were able to protect themselves with their beach umbrellas, normally used to block the sun’s rays.

The drizzle was also a mixed blessing at the Rancho Los Cerritos Historic Site, where officials planned to put on Mud Mania, a workshop on adobe construction. Events went on as scheduled--with a little extra mess--as the event’s answering machine reported that historians would open the workshop rain or shine.

“After all,” the message said, “it’s mud.”

At Dodger Stadium, many in the smallish afternoon crowd wore typical T-shirts, shorts and sunglasses--while carrying highly unusual umbrellas.

“It’s pretty bizarre--I’m a native Californian so it’s hard to believe,” said Bob Gifford, 38, a management consultant who was in a Forrest Gump “Stupid Is as Stupid Does” shirt.

Even if he had wanted to stay away, Gifford said, he couldn’t have because he had promised his 5-year-old son, Paul, that they would go to the ballgame.

“He wanted to come no matter what,” said Gifford. “And at that age, when you make them a promise, they don’t forget.”

Howard Feuerstein, 49, a New York City native wearing a Brooklyn Dodgers cap, said he enjoyed the weather because “it’s like being back East.”

With a light drizzle falling as the game was about to start, Alex Fitch, 10, was garbed in a different sort of rain gear--he wore his black leather baseball glove on his head.

“I hate the rain,” declared Fitch, adding that he loved the Dodgers.

At the annual Van Nuys Airport Aviation Expo, parachutists had to jump from altitudes a few hundred feet lower than planned because of the heavy cloud cover, and spectators took shelter under canopies and the wings of parked airplanes.

“In July, who would have thought they’d be used for the rain?” asked event spokeswoman Diane Scully.

Times staff writers Michael G. Wagner, Abigail Goldman and Nicholas Riccardi contributed to this story.