Nov. 17 (Bloomberg) -- Fire crews failed to gain much ground against two wind-driven blazes in Southern California's Riverside and Orange counties that have scorched almost 24,000 acres in the last two days.

While hot Santa Ana winds from the state's inland deserts have weakened, the region is expected to remain dry and hot until tomorrow, when cooler winds from the Pacific Ocean will pick up, according to forecaster AccuWeather.com.

The so-called Triangle complex of fires in the towns of Anaheim, Brea, Corona and Yorba Linda remained uncontained late yesterday. The fires have destroyed 64 buildings, including apartments and houses, the California Department of Forestry and Fire Protection said on its Web site.

``This is a pretty bad situation,'' said Michael Sager, a meteorologist at AccuWeather in State College, Pennsylvania. ``The heat and low humidity helps to pull moisture out of the plant life, so that it burns easier and burns hotter.''

Five thousand people have been evacuated and the fires threaten more than 3,500 residences. About 1,500 firefighters battled the blazes as wind gusts of as much as 45 miles (72 kilometers) an hour over the weekend complicated their efforts, said Daniel Berlant, a spokesman for the forestry and fire department.

Temperatures in Anaheim and Yorba Linda are expected to be as high as 92 degrees Fahrenheit (33 degrees Celsius), the National Weather Service said.

Temperatures to Fall

The winds will diminish as the week progresses because a high-pressure system is weakening as it moves east, said Carl Erickson, a meteorologist with AccuWeather. Temperatures will fall gradually into the upper 80s and humidity will increase, which should help curb the fires, he said.

The four cities are 26 miles to 48 miles southeast of Los Angeles.

Governor Arnold Schwarzenegger declared a state of emergency in Los Angeles, Riverside, Orange and Santa Barbara counties to free up state and federal funds to fight the fires, Berlant said.

A second fire, the Sayre fire near Sylmar in the San Fernando Valley, has burned around 10,100 acres and was about 40 percent contained, the forestry and fire department said. The blaze closed parts of Interstate 5, a major route running the length of the West Coast from Mexico to Canada.

The fire department said more than $2 million has been spent fighting the fire.

The third fire is 92 miles northwest of Los Angeles in the town of Montecito. It began Nov. 13 in the Los Padres National Forest and burned 1,940 acres (776 hectares). It was 80 percent contained after destroying 210 homes and damaging nine others.

To contact the reporters on this story: Dan Hart in Washington at dahart@bloomberg.net; Joseph Galante in San Francisco at jgalante3@bloomberg.net.

Last Updated: November 17, 2008 05:01 EST