The blaze, which was only 3 percent contained, has burned nearly 30 square miles near the coast about a mile south of Big Sur, officials said.
"Unfortunately, this fire is in an area that is going to be very difficult to stop, and expectations are there won't be any stopping this fire any time soon," said Mark Savage, a spokesman for the U.S. Forest Service.
Meanwhile, more dry lightning was expected toward the end of the week, although forecasters did not expect as severe an electrical storm as last weekend, when nearly 8,000 lightning strikes sparked about 800 fires across Northern California.
Gov. Arnold Schwarzenegger visited Monterey County on Wednesday to assess the damage and said he has called in the National Guard to help fight the fires.
"The fact is that when you have that many fires -- and there are still 700 fires left all over the state of California -- you get stretched thin with the resources," Schwarzenegger said.
The state's largest fire, located about 20 miles east of the Big Sur fire in a more remote area of the Los Padres forest, also continued to vex firefighters Wednesday, having scorched more than 92 square miles and destroyed two homes. The blaze, sparked by an escaped campfire on June 8, was about 71 percent contained.
The Monterey County fires have cost $33 million to fight so far.
Monterey sheriff's officials said mandatory evacuation orders were in place for both fires, but could not specify how many people were forced from their homes.
The governor also stopped Wednesday in Butte County, where 27 lightning-sparked fires covering about 8 square miles were threatening 1,000 homes. The blazes, which were only 5 percent contained, cropped up just as the county was recovering from a fire that charred 74 homes and 36 square miles earlier this month.
Schwarzenegger announced Wednesday that he allotted $20 million in emergency funds to help Butte County fight fire.
Fire crews from Nevada and Oregon have arrived to help California firefighters battle hundreds of blazes that are darkening skies over the San Francisco Bay area and Central Valley, causing public health officials to issue air-quality warnings.
"I just took off with the plane down from Los Angeles and, literally from Los Angeles all the way up here, there was smoke, so you can see that there's fire everywhere," Schwarzenegger noted at a news conference in Monterey County.
Areas hit the hardest by the weekend lightning storm also included Mendocino County, where 131 fires have burned more than 20 square miles and threatened about 500 homes, and the Shasta-Trinity Forest, where more than 150 fires have burned about 15.5 square miles and threatened 200 homes.
The storm struck California when the state was experiencing one of its driest years on record. Earlier this month, Schwarzenegger declared a statewide drought and directed agencies to speed up water deliveries to drought-stricken areas.
The next round of lightning forecast for later this week, however, could bring some moisture with it, said Dave Reynolds, a meteorologist with the National Weather Service. "We are certainly not as hot and dry as we were going into that event last weekend," he said.
Savage said that even with reinforcements from other states, firefighters ran the risk of being exhausted or injured in the months ahead given the brutal, early start to the wildfire season.
"We are not even to July and we have a record number of fires going on," he said. "It could be a very long season for our firefighters. Just extend the football season by eight or 12 weeks. It's a physical test of your endurance, but it could mean more wear and tear on our firefighters."MAP: Google Reference Map of California Fires
(From the Governor's Office of Emergency Services).