With fire risk high in parts of Minnesota, the state Department of Natural Resources has four new airplanes to control the wildfires that have resulted from an unusually dry start to spring.

FireBoss planes, which are updated models of the department's old fire-suppressing planes, are working to control wildfires across Minnesota as a drought overtakes much of the state.

The National Weather Service warned Friday of "very high grassland danger" for the southwest part of Minnesota. Officials say a fire in Aitkin County has burned 2,500 acres of land, but expect it to be contained Friday afternoon.

Star Tribune meteorologist Paul Douglas said 92 percent of the state is in moderate drought, adding that would it would take 2 to 6 inches of rain to pull out of it.

The DNR had nearly 50 requests Thursday for air missions on 16 fires across the state, said Bob Nelson, logistics program coordinator for the department's forestry fire section.

The state's high winds and low humidity prompted Gov. Mark Dayton to activate the Minnesota National Guard to assist in fire-suppression efforts.

Nelson said all four of the DNR's FireBosses were used Thursday, in addition to helicopters and other planes.

The FireBosses hold less water than the old planes, Nelson said, but they are faster.

"But the main thing is they're available," he said. "Our old aircraft were getting to the point where they were down a lot for service."

The Associated Press contributed to this report.

Anne Millerbernd is a University of Minnesota student on assignment for the Star Tribune.

Anne Millerbernd • 651-308-7126