The Department of Sustainability and Environment deployed spotter aircraft to help about 50 DSE and CFA firefighters on the ground after the first of about five fires started near the Wombat State Forest just before 2pm.

A DSE spokesman said smoke would remain visible in the area through the night as the fires continued to burn, but he said they were under control and no cause for concern.

"They are not spreading but they will put up smoke for quite a while," he said.

The spokesman said it was expected that more stormy conditions today would spark further fires in the region but both CFA and DSE were well prepared to tackle them.

Up to 17 appliances including trucks, tankers and bulldozers were on scene at Greendale yesterday to contain the blazes.