Northern Rockies Complex Incident Management Team 3
As of late afternoon on Sunday, August 24, 2025, the Derby Fire is 5,346 acres in size, with 0% containment and 648 personnel. Firefighters were able to conduct a successful burnout operation in the Horse Creek Drainage on the southern side of the fire before the afternoon rain. Line construction continued along the southwest and southeast edges of the fire.
Firefighters had strong support from aerial resources today, working with both retardant and water drops. Two military modular air firefighting systems (MAFFs) and supporting personnel arrived to assist with retardant drops. Aircraft aiding firefighting operations included four single-engine airtankers (SEATs), one large air tanker (LAT), two heavy helicopters, and a helicopter flying reconnaissance missions which also retrieved firefighters dropped off to tackle spot fires. When many aircraft are flying, in-air coordination is needed! Two air attack planes coordinated retardant and water bucket drops, a lead plane guided the large tankers and two Type 3 helicopters acted as communications repeaters.
The fire received widespread rain with heavier amounts in some areas. However, rain may not have penetrated denser tree canopies.
The photo below was taken late afternoon on Saturday, August 23, where the southeast edge of the fire grew. Look closely to see a helicopter dropping water along the fire edge. Photo by NIki Carpenter/Derby Fire.
