Although many other more serious fires have now been brought under control, 50 army members, two fire brigades and the army helicopter have been dispatched to the Muckish blaze.
Other fires including blazes at Ardara and Dungloe are now under control.
There are also other smaller fires in Milford and Buncrana which the fire service says it hopes to have under control by lunchtime.
Acting Chief fire officer Bobby McMenamin says people should still be on high alert to other fires breaking out.
“We still have to be very alert as we still have perfect conditions for more fires to break out. We are mostly on top of things while we are still fighting the fire on Muckish.
“We are asking people to remain vigilant and be on the lookout for fires. Even a small fire than turn quickly into a very large blaze because of the weather conditions,” he said.