"This incident is notable for its rapid expansion to over 1,400 acres within a month, the high number of personnel deployed, and the escalating estimated cost, reflecting significant resource commitment and potential impact on surrounding communities."
The Nature Grove wildfire, located 15 miles southeast of Hamilton in Ravalli County, Montana, was first discovered on August 23, 2026. The fire, caused by natural factors and managed by the U.S. Forest Service, grew rapidly from an initial 100 acres to 1,422 acres by September 16, 2026, with no containment reported throughout the timeline. Personnel numbers fluctuated, peaking at 345 firefighters on September 3, and the estimated cost rose from $200,000 early in the outbreak to $9,206,623 by mid‑September. Fire behavior evolved from active running and spotting to moderate flanking and backing, then to minimal smoldering and creeping as the fire stabilized. Despite the large area burned, containment remained at 0% and the fire continued to smolder with minimal activity.
Official source description: 15 Miles SE from Hamilton, MT
Minimal; Creeping; Smoldering; Backing
Good air quality. Outdoor activity is generally safe near this incident.
Nearest reporting station: Hamilton. Source: AirNow.gov (EPA).
The fire remains active with minimal smoldering and creeping behavior; residents in the vicinity should remain vigilant, follow local advisories, and be prepared for potential evacuation if conditions worsen.
IRWIN ID: {1DACBD6F-63CA-49E9-8D7B-3DBBD5BB31FF}
Discovered: Aug 23, 2026
Cause: Natural
Managing Agency: USFS
Est. Cost to Date: $9,250,623
Coordinates: 46.1535, -113.9243
Other wildfires that have recently been contained or dropped from official tracking in MT.
The Nature Grove Fire has burned 1,422 acres as of September 17, 2026.
The Nature Grove Fire has not yet reached any official containment.
The official cause has been listed as: Natural.
The Nature Grove Fire is burning in Ravalli, MT.
Yes, as of the latest official update, the Nature Grove Fire remains active.
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