By Ben Gruber
VENTURA, Calif. (Reuters) - Firefighters on Tuesday fought to take further control of a massive California wildfire, the fifth largest in the state's history, as relentless wind gusts and bone-dry weather were expected to persist throughout the week.
The blaze, known as the Thomas Fire, has burned 234,200 acres in Ventura and Santa Barbara counties about 100 miles northwest of downtown Los Angeles, and grew by about 2,500 acres overnight, according to the Department of Forestry and Fire Protection (Cal Fire) on Tuesday.
"Severe fire weather will continue to promote significant fire growth further into Santa Barbara County, threatening the communities of Santa Barbara, Carpinteria, Montecito and Summerland," Cal Fire said in a statement.
Strong wind gusts of up to 40 miles per hour (65 km per hour) and extremely low humidity expected through Thursday will pose a challenge to firefighters, the National Weather Service said Monday evening.
Gusty offshore winds will continue to threaten structures in Ventura County and surrounding areas as well as the communication infrastructure, which could affect public safety, such as cellular services, according to Cal Fire.
Nearly 7,000 firefighters were battling the Thomas Fire, which has destroyed almost 900 structures including more than 690 homes, Cal Fire said. The inferno, which threatens about 18,000 structures, was 20 percent contained by Tuesday morning.
Efforts to combat the wildfire, which has displaced more than 94,000 people, have cost more than $48 million to date.
Dry vegetation that has not burned in 50 years has acted as fuel for the fire in the mountains southeast of Santa Barbara and northwest of Ventura counties, Cal Fire spokesman Ian McDonald said.
"Because the slopes are so steep and the terrain is so rocky, it is actually quite dangerous," he said. "We are not going to put firefighters in harm's way halfway up a steep rocky slope. We are going to wait for the fire to come to us and extinguish it where it is safe."
Public schools in Santa Barbara and school districts nearby have canceled classes this week and will not reopen until the annual winter break is completed in January, said Santa Barbara Mayor Helene Schneider.
Some of the other fires burning over the past week in San Diego and Los Angeles counties have been largely brought under control by the thousands of firefighters on the ground.
The Creek and Rye fires in Los Angeles County were both at least 90 percent contained, officials said, while the Skirball Fire in the exclusive Bel Air neighborhood of Los Angeles was 85 percent contained.
North of San Diego, the 4,100-acre (1,660 hectare) Lilac Fire was 90 percent contained on Monday after destroying 151 structures.
(For a graphic on 'California wildfires' click http://tmsnrt.rs/2ADhxIj)
(Additonal reporting by Brendan O'Brien in Milwaukee; Editing by Jeffrey Benkoe)