NORTHERN CALIFORNIA — Cal Fire said Friday that after nearly a year of work, its investigators have not been able to determine the cause of last year’s Glass fire.

The Glass fire started in Napa County on Sept. 27, 2020, at 3:48 a.m., and burned a total of 67,484 acres and destroyed 1,555 structures in Napa and Sonoma counties.

Cal Fire said its investigators were immediately dispatched to the Glass fire and began working to determine the origin and cause of the fire.

“After a very meticulous and thorough investigation, which included months of follow-up on information provided by the public, not enough evidence was available to conclusively identify the cause,” Cal Fire said in the Friday statement.

Cal Fire said the fire’s cause is currently undetermined pending any additional information or evidence that could lead to the determination of the cause.

Tinder dry vegetation and strong winds combined with low humidity and warm temperatures contributed to extreme rates of fire spread which contributed to the difficulty in determining the cause of the fire, Cal Fire said.