RICHARD NIXON: 1913-1994 : Rain, Hail Pelt Library Mourners : Weather: Unseasonable storm may return during outdoor Nixon burial. Chilly temperatures likely.

Mourners and onlookers who had gathered at the Richard Nixon Library & Birthplace here Tuesday got caught in a rare Southern California hailstorm and an unseasonal downpour of rain, which is predicted to make a return appearance during the outdoor funeral of Richard Nixon today.

There was a 30% chance of rain, partly cloudy skies and cool temperatures that likely would not rise above 60 degrees today, according to Curtis Brack, a meteorologist with WeatherData, which provides forecasts for The Times.

The hail and rain hit with a Pacific storm that was passing over the Southland, a more common occurrence in the winter than in the spring.

“For this time of year in Southern California, it’s unusual. Having heavy rains and strong thunder is something you might expect more in the winter months,” Brack said, adding that a strong trough of low pressure in the upper atmosphere in Southern California caused the rain, which periodically was transformed into golf ball-sized hailstones.

At first only the blocks immediately surrounding the Nixon library were pelted with rain and hail Tuesday morning. But by mid-afternoon, many well-prepared onlookers at the library, huddling under umbrellas and too dogged to give up their place in line for the afternoon viewing of the presidential casket, were drenched as the occasional showers turned into a downpour.

There was also thunder--one thunderclap so loud that it set off a car alarm--lightning and hailstorms in Yorba Linda at 2:50 p.m. and 3:35 p.m., which experts consider unusual and don’t expect today.

Brack said that because the storm system is weakening, any rain in Yorba Linda today will likely be light. “We are not expecting any thunderstorms,” he said, and there were no flood or storm warnings in effect for Orange County today.

The amount of rainfall was no more than 1.3 inches at any one place in Orange County Tuesday morning, officials said, and no more than that is expected today.

But unseasonable weather took its toll Tuesday evening. At 4:15 p.m., the California Highway Patrol closed Carbon Canyon Road from Valencia Avenue to the San Bernardino County line because of icy roads and mudslides around Carbon Canyon Regional Park. Bad road conditions also caused a 10-car pileup at 3:45 p.m. on Carbon Canyon Road north of Olinda Place in Brea, where area residents reported snow and hail. Ice and hail were also reported on the Riverside Freeway near Weir Canyon Road, officials said.

Also, about 20 weather-related accidents on Orange County freeways occurred Tuesday, most of which did not result in injuries. Officials blamed the pileups not only on the rain but motorists’ stubborn refusal to slow down in bad weather.