July 10 (Bloomberg) -- Temperatures soaring past 100 degrees again today raise the risk of new or expanded fires across much of California, where drought and lightning caused an explosive early start to the 2008 fire season.

About 10,000 residents of Paradise, 82 miles (133 kilometers) north of Sacramento, including 68 hospital patients, were evacuated during the night because of encroaching fires, Republican Governor Arnold Schwarzenegger said yesterday. They joined residents of Concow, 6 miles to the east, who were evacuated yesterday.

Excessive heat and high fire risk warnings are posted for a 681-mile stretch from southern Oregon to Los Angeles as a high pressure area sits over the West. Temperatures on July 8 hit 107 degrees Fahrenheit (42 Celsius) in Modesto, breaking a record of 102 for the date in 2006, while Redding saw a high of 110, just shy of the 112 record for the date set in 2007.

``Because of the very high temperatures, fires could flare up again anyplace in the state,'' Schwarzenegger said at a press conference yesterday in Sacramento.

Most of the state is covered today by a red flag warning, which means conditions are right for ``explosive fire growth.''

Since June 21, a total of 1,781 fires have burned 675,631 acres throughout California and have cost $276 million to fight, according to state and federal fire reports.

Currently, 18,954 firefighters are battling 323 fires that threaten 15,751 homes and buildings and have forced the evacuation of thousands, including some residents of Big Sur, 150 miles south of San Francisco, and Goleta, about 84 miles north of Los Angeles.

Foreign Assistance

And firefighters from New Zealand, Australia and Canada may be joining the battle against wildfires burning across California, a federal agency said. U.S. officials are negotiating with fire services in the three countries to reinforce state and federal firefighters now engaged in battling the blazes, said Don Smurthwaite, a spokesman for the National Interagency Fire Center in Boise, Idaho.

``Another indication that it is a challenging fire season is when we start looking at international resources,'' Smurthwaite said by telephone.

The trouble for California may just be starting because the state still has to get through its traditional fire season starting in late August and it has dense forests that are susceptible to burning.

``I hate to say it but I am afraid it is going to be more of the same,'' said Chad Oliver, a forestry professor at Yale University's School of Forestry and Environmental Studies in New Haven, Connecticut. ``I am afraid that this is going to be a continuous problem for the summer.''

More Severe Fires

Scientists in the past two decades began predicting the western U.S. would begin to see hotter, more severe fires because of policies begun in the 1930s to prevent natural fire cycles from occurring, said Oliver, who also is director of Yale's Global Institute of Sustainable Forestry.

By stopping fires from thinning forests there are more trees and underbrush to burn, providing fuel for the blazes to become hotter and more destructive, Oliver said. In the past, many older trees would survive, however the fires now burning tend to destroy entire forests.

Rainfall in northern California has been 30 to 40 percent below average and the snow pack in the mountains, which provides water in the form of runoff, was 35 percent less than it should be, Kopps said. In southern California, the past rainy season, which ends in June, was among the ``driest on record,'' he said.

On June 4, Schwarzenegger declared a drought because of two years of low rainfall and little snowmelt.

``For the areas of Northern California that supply most of our water, this March, April and May have been the driest ever in our recorded history,'' Schwarzenegger said in a statement.

Funds Sought

The amount of acreage burned hasn't set records. In 1987, for example, 13,476 fires burned 873,000 acres, according to Cal Fire statistics. What surprised fire officials this year was the early and ferocious start to the season, with 1,700 fires starting in a two-day period, most set off by lightning.

Mike Richwine, a division chief with the state forestry division, known as Cal Fire, called the number of blazes ``unprecedented this early in the season.''

``It is both surprising and sad that it started this early,'' Oliver said. ``It is frightening.''

Schwarzenegger said the state fire season, which usually begins in late August, has now become a year-round phenomenon. He has asked lawmakers for $70 million to boost the state's firefighting capability.

At Big Sur, the Basin Complex fire is about 27 percent contained, according to the U.S. Forest Service. The blaze, which has consumed 85,717 acres and engaged 2,275 firefighters, has been fueled by trees killed by Sudden Oak Death disease.

As many as 1,500 people were evacuated from the area, though many are being allowed to return to their homes.

Near Goleta, the Gap fire is about 55 percent contained and has burned nearly 9,785 acres since July 1, according to the Forest Service. The last time the area saw a wildfire was 1955 and there is ample fuel to keep it going.

To contact the reporter on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net.

Last Updated: July 10, 2008 03:00 EDT