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Growing armies of firefighters battled wildfires in the heart of California’s sequoia country on Wednesday.

A big increase in personnel put more than 1,400 firefighters on the lines of the KNP Complex fire in Sequoia National Park, fire information officer Ana Beatriz Cholo said.

The fire remained a threat to the park’s famed Giant Forest. But the weather was expected to clear out smoke and allow aircraft to begin operations against the flames.

Weather conditions that trap smoke have the benefit of reducing fire activity but also can make it unsafe to fly.

The fire earlier entered a portion of Giant Forest, but none of its famous gigantic trees were harmed, officials have said.

For decades, the grove of 2,000 sequoias has been regularly subjected to prescribed burns that clear out other types of vegetation that could intensify fire and carry it to the crowns of the trees.

Fire-resistant material has also been placed around the bases of some of the most famous forest inhabitants, including the General Sherman Tree, the largest in the world by volume.

The KNP Complex began as two fires ignited by lightning strikes on Sept. 9. They later merged into one blaze that has scorched more than 44 square miles (114 square kilometers) with zero containment, forcing the closure of Sequoia National Park. Most of adjacent Kings Canyon National Park is also now closed.

To the south, the lightning-sparked Windy Fire grew to 49 square miles (127 square kilometers) in the Giant Sequoia National Monument area of Sequoia National Forest and containment crept up to 7%.

Nearly 1,300 firefighters were assigned to the blaze.

“The fire’s active, but we’ve got a good number of staff out there,” information officer Kate Kramer said.

The Windy Fire has affected several sequoia groves, but the extent of any damage has yet to be assessed. One big tree on the Trail of 100 Giants was confirmed to have sustained some burning.

Giant sequoias can benefit from fire if it is not too intense.

Historic drought tied to climate change is making wildfires harder to fight. It has killed millions of trees in California alone. Scientists say climate change has made the West much warmer and drier in the past 30 years and will continue to make weather more extreme and wildfires more frequent and destructive.