Record Heat Sears Coast; Fire Danger Is ‘Explosive’ : Weather: San Juan Capistrano’s 95 is the highest in the nation. Cooling to 70s is expected for Thanksgiving.

Record temperatures prompted thousands of Orange County residents to brush aside holiday preparations and dash outdoors Sunday as bone-dry desert winds whipped up visions of summer rather than sugar plums, shopping or snow skiing.

Temperatures soared into the 90s for the second straight day as county firefighters remained on alert, wary of what one fire official called “explosive fire conditions” in the tinder-dry hills and mountains on the county’s perimeter. Winds gusting up to 35 m.p.h. swept skies blue but elevated the fire danger, already considered critical after three years of below-average rain.

A brush fire that broke out at 10:30 a.m. near Riverside had charred more than 300 acres by 9 p.m. and had inched into the Corona-Norco area. A Riverside County Fire Department spokesman said some homes were threatened, but no evacuations had been ordered.

At dusk, quick work by county firefighters prevented a brush fire near rural Black Starr Canyon from consuming more than an acre before it was extinguished. But more than 150 acres of brushland were blackened in San Dimas and the adjacent Angeles National Forest in Los Angeles County, and firefighters were concerned that winds might kick up Sunday evening and fan the flames.

For the second straight day, San Juan Capistrano was the hottest spot in the nation. The mercury on Sunday in the mission city was 95, shattering the previous Nov. 19 record high for Orange County of 87, set in Santa Ana in 1917.

The average Orange County temperature for mid-November is 73 degrees.

Cooler temperatures are expected to return beginning today, with highs inland in the low to mid 80s. Temperatures should be in the mid 70s on Thanksgiving day with patchy low clouds and coastal fog followed by afternoon sunshine, according to WeatherData Inc., which provides forecasts for The Times.

But few people were talking turkey on Sunday. The weather was the hot topic, and San Juan Capistrano City Councilman Lawrence F. Buchheim even took a measure of civic pride in his city’s record reading.

“Well, I didn’t know San Juan had made it as the hottest spot in the nation, but I’m glad to hear it,” said Buchheim, wryly adding that Sunday’s weather rivaled the heat often generated at council meetings. “San Juan Capistrano is always a special place, and here we’ve made it again.”

The hot weather proved a bonanza at one of the city’s most colorful watering holes. Bartender Pito Olivares at the Swallows Inn said patrons were “asking for doubles. . . . It’s hot.”

Many sought relief at the beach--a strange concept for much of the nation, caught in the midst of pre-Thanksgiving chill and ice. But the calendar didn’t stop Tracy Wilburn from “beaching it” Sunday at Corona del Mar.

“It’s outrageous on the sand,” said Wilburn, a freshman at Orange Coast College in Costa Mesa. “I talked to my best friend at college in Chicago today and she’s been wearing sweaters since early October. I haven’t been out of shorts yet this fall.”

The turnout on San Clemente’s main beach was typical of the assault along the county’s 42-mile coastline, which afforded crystal-clear views of Catalina Island. Marine safety officer Steve Lashbrook said a typical weekend crowd in November is about 3,500 people, but Sunday more than 8,000 flocked to the sand where temperatures at the water’s edge were near 80.

Elsewhere in the county, the mercury hit 91 in Santa Ana, 89 in Anaheim and 88 in El Toro. Overnight lows have generally been in the upper 50s.

A strong stationary ridge of high pressure over the Nevada-Utah border is keeping any threat of rain well to the north of California as the jet stream that carries storms and cold air from the Gulf of Alaska has been pushed into Canada.

The high pressure also generated the strong offshore flow, sending warm desert air through the mountain passes into Southern California. As the air descends in elevation, it heats up, so it is actually as warm or warmer at the coast than inland. For example, it was 89 in Newport Beach, while Death Valley was just 82, and the high in the desert resort town of Palm Springs was 90.

The heat did little to jump-start holiday gift buying, reported disappointed merchants.

One South Coast Plaza clothing store owner, whose shop is decorated for Christmas, said it was so warm inside he turned on the store’s ceiling fans.

“It’s hardly the type of cozy holiday weather to send people rushing to shop,” bemoaned Ron Werner, a menswear merchant. “I’ve got snowflakes on my windows and it’s baking outside. It’s like summer.”

Werner wasn’t the only merchant steaming Sunday. The lack of snow in the local mountains and the Sierra has meant a slow start of the ski season for retailers.