Steamy Summer a Welcome Relief for Firefighters : Weather: Unseasonal conditions inhibited fire activity, but a hotter, drier and windier pattern is emerging that could spell trouble this fall.

Thanks to unusually humid conditions, Orange County experienced one of its safest summers in memory, according to fire officials.

Though unbearably sticky to many, the humidity--just one of several unusual aspects of the summer weather--contributed to a period of welcome calm for the firefighters who roam the county’s 160,000 acres of wilderness.

“In August, we had hot weather--a series of days over 90 (degrees)--but we also have had humid days, and a fire just doesn’t burn as quickly,” said Kathleen Cha, spokeswoman for the Orange County Fire Department. “And there have been no excessive winds. . . . Things have been very quiet.” Firefighters handled only about a dozen brush fires that spread beyond an acre, none of which touched a home or claimed a life.

Overall, the summer of 1992 featured an odd week of rain followed by 56 consecutive days of warmer-than-usual overnight temperatures, the warmest ocean water in recent memory and a record-breaking heat wave in August.

“It was absolutely unusual,” said Rick Dittmann, meteorologist for WeatherData Inc., which provides weather information to The Times. “It was unusually humid this summer. We went through a period of time when we were affected by diminishing, dying, decaying hurricanes that sent a swath of moisture into California.”

For water lovers, the summer was especially inviting. Usually in summer, the surface of the ocean measures about 65 degrees. But in early August, the ocean warmed to more than 70 degrees for nine consecutive days.

“I have never seen it that warm for that long,” said Mike Beuerlein, a marine safety officer at the lifeguard station in Huntington Beach who has been tracking ocean temperature there for 11 years.

Meteorologists said the warm ocean temperatures, caused in part by a weakening El Nino condition, set up an intriguing July and August.

In early July, it rained three times in six days for a grand total of only .16 of an inch, but it was enough to raise the eyebrows of meteorologists. “For Southern California, it was significantly unusual; .16 of an inch of rain is not like it is going to break a drought, but the average for the month is only .01,” Dittmann said.

Early July also marked the beginning of a two-month stretch of warmer-than-usual temperatures and humid conditions brought on in part by tropical hurricanes. The warm ocean water allowed tropical storms and hurricanes Darby, Estelle, Frank and Georgette to track north while maintaining strength, specialists said.

For 56 consecutive days, the overnight low temperatures did not reach the usual seasonal low. That trend was interrupted Aug. 31 and then resumed for the first three weeks of September.

Mid-August will be remembered for bringing the first heat wave of the year--a record-breaker. Ninety-four-degree temperatures were recorded in Santa Ana on Aug. 15 and 16, breaking or tying the record highs for those dates. On Aug. 17, it reached 96 degrees, another record.

A contributing cause of the heat wave was the westward migration of a subtropical high-pressure system over the western United States. As a result, moist air from the Gulf of California that would normally affect Arizona descended on Orange County instead, Dittmann said.

Those summer conditions, so favorable for firefighters, are giving way to a hotter, drier and windier pattern that could create a potentially disastrous autumn fire season, officials said. The largest fire of the summer occurred Sept. 20, when about eight acres were scorched off Santiago Canyon Road near Modjeska, in the southeastern region of the county.

“There is a perception out there that fire season is only during summer,” Cha said. “When we have winds, we have the worst fires. And if you look at the history of Orange County, some of the worst fires hit in October and November.”

Recently, the frequency of vegetation fires has risen to three to four per week, according to fire officials. And dry Santa Ana winds, which were absent this summer, are expected to sweep through the county in the coming months.

“Right now, vegetation and brush is very brittle,” Cha said. “Everything that grew this summer is now dry.”

Because the mercury began to rise again into the mid-90s during late September and no rain has fallen since early July, the county is now parched and poised for a threatening fire season.

“We are walking into a very dangerous situation,” Cha said.