Rain Holds Off and Coolness Prevails in Prelude to Fall : Weather: Sunday marks the advent of autumn and the wet season. Weatherman says it will stay dry for a while.

Orange County residents were treated to a prelude to fall Thursday as temperatures dipped into the mid-70s and overcast skies threatened rain.

Though little, if any, rain is expected to fall this weekend, the cooler temperatures are expected to stick around for a while--that is, unless the Santa Ana winds start to blow.

Beach-goers couldn’t tell much of a difference between summer and autumn weather Thursday as people made their way to parks and beaches for a moment in the sun.

“There is no comparison with the weather, the climate, the view,” Philadelphian Robert Klug, 59, said as he took in the ocean view from Laguna Beach’s Heisler Park. “Personally, I would say the weather (here) was ideal.”

Fall begins Sunday, the day that also officially marks the beginning of this year’s much-needed rainy season. But meteorologist Marty McKewon of WeatherData, which provides forecasts for The Times, said Thursday that he doesn’t expect to see the kind of rains necessary to relieve drought-stricken areas any time soon.

“We’re calling for normal temperatures and drier than normal precipitation--which isn’t good news, I know--for the next month,” McKewon said.

Weather for this weekend, however, is expected to be a bit cooler than normal. McKewon said the upper-level low pressure that has carried a 20% chance of rain for Orange County today is expected to move northward Saturday. By Sunday, the skies should be clear, leaving only the cooler temperatures behind to greet the first day of autumn.

Despite a 20% chance of rain Thursday, no rain was recorded in the county. In fact, no rain has been recorded all month, unlike traditional September readings of about a quarter of an inch.

The average high temperature for September is about 82 degrees while Thursday’s high was 74. Temperatures are expected to remain about 5 to 7 degrees cooler than normal through the weekend, McKewon said.

While the change of seasons is not heralded in Southern California by a carpet of brilliantly colored leaves, there are subtle signs of change. For example, brown hills turn green after the first rains and California flowers begin to bloom, said Charles O’Neill, museum scientist for the UC Irvine arboretum.

“The first thing I hear from people who don’t know is always, ‘Southern California doesn’t have a change of seasons.’ That’s just not true,” O’Neill said. “There is a definite change of seasons here. Southern Californians who live here can sense the change, just as those from the East can, only theirs is more drastic with the snow.”

And the subtle change is just fine with visitors to Laguna Beach’s Heisler Park.

“Coming from the East Coast, New York, this is just a treasure,” said 16-year Laguna Niguel resident Charlotte Lockwood, 75, as she rested from her walk along the shore Thursday. “Today, I thought I’d just come down and enjoy it fully.”