PHOENIX (AP) — Arizona had one of its worst wildfire seasons in nearly a decade last year, state Department of Forestry and Fire Management officials said Wednesday.

They said statistics show 2,520 wildfires burned 978,519 acres of state, federal and tribal lands in 2020. Of those fires, wildland fire investigators said 82% were human caused.

In comparison, 1,869 wildfires burned 384,942 acres on all land jurisdictions in 2019 and some 2,000 wildfires burned an estimated 165,000 acres in 2018.

Arizona’s most severe and destructive wildfire seasons came in 2011 with 1,988 fires charring more than 1 million acres.

Authorities said that among the factors for last year’s severe wildfire season was unseasonably warm conditions, a lack of moisture, an overabundance of fuels across Arizona’s central region and within the Sonoran Desert, and increased recreational traffic across the state.

Arizona’s nonexistent monsoon season also exacerbated the problems and pushed fire activity well into the fall with October’s 9,537-acre Horse Fire on the Prescott National Forest.

The lack of precipitation kept fire restrictions in place through November, according to forestry officials.

“The extreme drought conditions, excess ground fuel and inadequate moisture created fast moving, large-scale fires,” John Truett, fire management officer for Arizona’s forestry department, said in a statement.