The hot, humid weather that continues to drive thousands to the coast will give way to scattered showers, cooler temperatures and possible thunderstorms today in the deserts and mountains.
"The mountains are going to get a 50% chance of rain, and I would say it's about a 30% chance that there will be scattered showers in Orange County on Monday," said Jeff House, a meteorologist with WeatherData, which provides forecasts to The Times.
With rain in the forecast, temperatures will cool slightly from Sunday's stifling heat, which saw the mercury climb to 97 in Santa Ana. The high tied a record set in 1965.
El Toro was the warmest area of the county at 98 degrees, House said.
Flash flood watches were in effect for Southern California desert areas until early today. On Tuesday, clouds will remain, but drier weather is predicted.
The cause of the expected thunderstorm activity is remnants of former tropical storm Frank, which came up from Mexico and arrived in Orange County on Sunday.
On the coast, lifeguards said dawn on Sunday "was absolutely gorgeous," with a wisp of clouds in the sky. But throughout the day, dark clouds filled in, causing relative humidity to skyrocket to more than 70%.
"In the afternoon, we started getting clouds and winds blowing out of the southeast. From our lifeguard tower on the pier, we could see these big thunderheads over the desert," said Matt Karl, a Huntington Beach lifeguard.
Hot inland temperatures in the 90s prompted many people to leave the heat and spend time outdoors, either in parks or at the beaches.
"We had about 100,000 people on our beaches [Sunday]. It was extremely crowded," Newport Beach lifeguard Brian Ismagil said.
Rescues were down, however, because of the relatively small surf, which Ismagil estimated at 1 to 3 feet. Newport reported 15 to 20 rescues; Huntington Beach had fewer than 15.
During the hottest part of the day, firefighters were dispatched to a blaze about 11 miles east of San Juan Capistrano that temporarily shut down the California Wildland Firefighters Memorial Highway, formerly Ortega Highway, a main connector between Lake Elsinore and Orange County.
Because of the potential for the fire to spread, the Orange County Fire Authority launched a substantial attack early that included two helicopters and a fixed-wing aircraft to battle the 2 1/2-acre blaze, which was in rough terrain.
"It took us about 45 minutes to bring the fire under control," said Capt. Scott Brown, a Fire Authority spokesman. The fire was reported about 4:20 p.m.
No buildings were burned. No injuries were reported, and the cause of the fire is under investigation.