In the wake of California wildfires, upwards of 10,000 trees weakened by fires, drought, disease or age must be removed, work that will keep a nearby highway closed to visitors who seek the world’s two largest sequoia trees.

The hazard trees could potentially fall onto people and cars on the section of State Route 180 known as Generals Highway, or they could create barriers for emergency and fire response, the Sequoia and Kings Canyon national parks said on Friday.

The highway is closed due to the KNP Complex blaze, which was 60 per cent contained after burning 138 square miles (357 square kilometers) of the forest, and will remain blocked off to visitors after the fire is out while saw crews cut down trees and trim branches. Cooler weather has helped slow the flames and the area was expected to see rain starting Sunday.

The highway connects Giant Forest, home to the General Sherman Tree, which is considered the world’s largest by volume, and Grant Grove, home to the General Grant Tree, the second-largest tree in the world. The trees along the highway include sequoias, pine, and conifer trees, said fire spokeswoman Kimberly Caschalk.

The KNP Complex has been burning since September 9, when lightning ignited two fires that later merged.

Forest officials said earlier this month the fires may have killed hundreds of giant sequoias, but the full extent of the damage has not been determined.

The fire’s impact on giant sequoia groves was mixed. Most saw low- to medium-intensity fire behaviour that the sequoias have evolved to survive, and the most notable trees survived.

Firefighters took extraordinary measures to protect the sequoias by wrapping fire-resistant material around the bases of some giants, raking and clearing vegetation around them, installing sprinklers, and dousing some with water or fire-retardant gel.

On Friday, forest staff unwrapped the base of the General Sherman tree after danger from the fire had passed.

“We’re confident that tree is relatively safe,” Caschalk said.

Drought in the West tied to climate change is making wildfires harder to fight. Scientists say climate change has made the West much warmer and drier in the past 30 years — meaning the rain and snow that does fall is likely to evaporate or absorb into the soil — and will continue to make weather more extreme and wildfires more frequent and destructive.

Recent storms have helped contain some of the nation’s largest wildfires this year, including one that threatened the popular Lake Tahoe resort region this summer and is now 100 per cent contained after snow blanketed the western side of the blaze and rain dropped on the eastern side. But this week’s storms won’t end the drought that’s plaguing California and the western United States.