Some 100 hectares of forest area on Mount Ciremai was gutted by fire, Agus Yudantara, spokesman of the Mount Ciremai National Park, said here on Wednesday.
The wildfire, razing bushes and grasses, was triggered by the current prolonged drought, he added.
A joint team, comprising military and police personnel, local fire fighters, and volunteers, was deployed to extinguish the blaze.
On Mount Slamet, fire razed a pine forest area belonging to the state-owned forestry company Perhutani, according to Captain Sarmin of the Pemalang military district.
Local authorities and volunteers had tried to put out the fire since Tuesday evening, but due to difficult terrain, the fire was still unable to be extinguished.
The ongoing severe dry season has triggered wildfires on several mountains on Java Island.
Among the affected mountains are Mount Sindoro in Central Java, Mount Lawu in the border of the provinces of Central and East Java, Mount Argopuro in East Java, Mount Sumbing in Central Java, and Mount Sadran in East Java.
Reporting by Khaerul Izan and Sumarwoto
Editing by Fardah