Record Heat Makes Us Wish for Clouds Again : Weather: The humidity and heat should last about a week. Then overcast conditions are expected to return.

After a summer of overcast skies and cool temperatures, the mercury at Lindbergh Field soared to 94 degrees shortly after noon Monday, making it the hottest Aug. 12 on record, said Wilbur Shigehara, forecaster for the National Weather Service in San Diego. The previous record of 88 degrees was set in 1946 and matched in 1965.

“It feels like summer,” Shigehara said. Lindbergh Field has not seen temperatures that high since June 26 of last year.

The previously hottest day this summer, with a temperature of 78, was Sunday, he said.

To beat the heat, residents and visitors headed for the beaches, where lifeguards reported larger than normal crowds from Ocean Beach to Torrey Pines.

“The crowd was rather large for a Monday,” said lifeguard Marty Armstrong. An estimated 53,600 people were at San Diego city beaches, contrasted with an average of 35,000 for a typical summer Monday, he said.

“We’ve got a good double crowd and we haven’t had too many rescues because there hasn’t been an increase in the waves,” he said. The ocean temperature was 68 degrees, with waves at 2 to 3 feet.

The heat wave is driven by a tropical storm, rapidly falling apart off the coast of San Diego, and hot winds blowing from the mountains to the sea, like the flow of a Santa Ana, he said.

Hurricane Hilda was spawned off the coast of Acapulco last Wednesday but never clocked wind speeds of more than 40 m.p.h. Hilda, downgraded to a tropical storm, is 450 southwest of San Diego, but there’s not much left to it, Shigehara said.

But moisture and heat from the storm, and the hot westerly winds pushed the mercury up throughout the county. The lowest maximum temperature, 74, was recorded at Mt. Laguna, but most areas reported highs in the uppers 90s. Alpine registered 96; Chula Vista, 96; Coronado, 87; Del Mar, 90; El Cajon, 98; Escondido, 98; Lemon Grove, 98; Miramar, 102; National City, 96; Oceanside Harbor, 91; Poway, 99; Santee, 102; Vista, 98.

Shigehara said he didn’t expect record-breaking temperatures today. Lindbergh Field is expected to reach a high of 85 degrees.

Traces of rain fell Monday, and with a 30% chance of rain forecast, “we could get a quarter to a half inch of rain through Wednesday,” he said.

Most of the moisture, however, is flowing north toward Los Angeles and Santa Barbara. In San Diego, the humidity dropped from a high of 81% at 4 a.m. Monday to 37% at 4 p.m., and a flash-flood watch issued for the mountains and deserts was canceled as Hilda continued to weaken, Shigehara said.

Hilda will still pump moisture into San Diego, keeping the weather warm and humid and skies partly cloudy, he said. The summer-like weather should last about a week, he added.

“We still have to watch out for summer thunderstorms caused by moisture coming up from the Sonora region of Mexico,” he said. Long-range weather charts show the marine clouds coming back and temperatures cooling down early next week, he added.

The summer weather has been welcome news for the California Department of Forestry, which fights large-scale grass and brush fires.

“We’re down in the number of fires and the acreage,” said forester Steve Davis, who oversees vegetation management. “Our fuel moisture is running higher than last year, meaning there’s more moisture in the brush this year than last year.”

The higher humidity has been a bonus. One of the things that drives a fire is dry air, he said. The drier the air, the drier the surroundings and the more readily things burn, he added.

Within the past three weeks, the forestry department has fought a 200-acre fire near Poway and an 80-acre fire north of the Wild Animal Park. Weather and humidity prevented those fires from becoming even larger, he said.

As a safeguard, the forestry department plans some controlled burns to break up large areas of grass and brush, he said.

However, “if the weather changes to Santa Ana conditions, we won’t be able to do the burns,” he said.