FRESNO . (AP) — Fire crews aided by light rain, cooler temperatures and high humidity were able to slow a 1,800-acre wildfire in the Sequoia National Forest.

The fire remained 35 percent contained Tuesday morning and didn't grow as quickly overnight as officials had feared thanks to the favorable weather brought by a freak June cold front in California.

The steep, rugged Sierra Nevada terrain and the location of the fire in a federal protected wilderness area have added to the challenges faced by firefighters. Without roads, getting ground crews to the front lines in a remote region 90 miles east of Fresno has been difficult.

"Crews are having to hike in quite a way, and some are being flown in by helicopter because of the access issues," said Raj Singh, spokesman for the coalition of fire agencies assigned to the blaze known as the George Fire.

Fire officials hope to take advantage of cooler temperatures during the day and are calling for more personnel to join the 713 already on the lines. Officials say the blaze is being battled by hand because bulldozers and fire retardant are not allowed in the wilderness area.

The fire started Friday and quickly moved from the Freeman Creek Giant Sequoia Grove into the Golden Trout Wilderness. It did not significantly damage the grove, officials said.

On Monday high winds pushed the fire across hand-dug lines, but the change in weather helped firefighters gain an advantage.

"All of the lines are holding right now," Singh said.

Often fires are allowed to burn in U.S. forests because it restores the forest ecology. Because of dry conditions and a lack of snowfall this winter, the U.S. Forest Service decided to aggressively fight the fire for fear it would rage out of control.

Meanwhile, investigators are asking for the public's help in determining the cause of the fire.

Many backcountry fires are started by lightning. But a fire spokesman said there was no lightning in the area when the fire started.