Weather may complicate the work of hundreds of firefighters in the days ahead as they battle two out-of-control California wildfires.
Lightning strikes associated with thunderstorms near Yosemite National Park could spark new fires near the 2,100 acre blaze there.
And ongoing hot, dry and windy conditions near the 3,800 acre Sand fire near Placerville could fan flames, a Sacramento-based National Weather Service meteorologist said Sunday -- encouraging that fire to spread quickly through drought-ravaged, dried-out vegetation.
"Anytime we have gusts along with high temperatures and low humidity it's a recipe for aggressive fire growth," Drew Peterson said.
His office was predicting high temperatures in the region near the Sand fire Sunday, ranging from the extreme upper 90s into the low 100s, with humidity hovering around 10% -- a level that presents a significant fire danger.
Weather service meteorologists also expected gusty winds in the area, Peterson said, noting that "it doesn't take much wind to amplify the speed and spread" of the fire.
Adding to the danger, he said, was low "fuel moisture" -- drier-than-usual vegetation for this time of year, thanks to ongoing drought conditions.
Peterson said the weather was expected to remain similar throughout the rest of the week.
Earlier Sunday, California Department of Forestry and Fire Protection spokeswoman Lynne Tolmachoff said her agency expected it to take at least that long before firefighters fully contained the Sand fire.
To the southeast in Yosemite National Park, meteorologists said they were unsure how expected storms in the area might impact the other large fire in the state, which had been burning for about a day.
"A thunderstorm is a mixed blessing," said Hanford, Calif.-based National Weather Service meteorologist Gary Sanger. "You get rain, but you also run the risk of lightning and more fires, and gusty winds which can cause the fire to spread."
Last year, the 410-square mile Rim fire burned an estimated 77,000 acres, or 120 square miles, within the park. Sparked in mid-August by an illegal campfire in the Stanislaus National Forest, the Rim fire was not fully contained until late October.
Peterson said that the Sand fire had been easier to access for firefighters than the remote Rim fire.