The Rocky Fire began at a property on Morgan Valley Road, east of
Clearlake in Lake County, at about 3:30 p.m.
PDT on Wednesday, July 29, when a gas-powered water heater in an outbuilding caught fire and set nearby vegetation alight. Firefighters were initially dispatched to the incident based on a report of a structure fire on Rocky Creek Road; a second fire was later reported on Morgan Valley Road with an unknown cause. The fire was named the Rocky Fire for its proximity to Rocky Creek, which flows north of Morgan Valley Road. High temperatures and winds helped the ensuing fire spread rapidly as it entered thick brush and woodlands, advancing forward by
ember spotting. By that night, the Rocky Fire spanned in area and was the largest active wildfire in Northern California. Toward the end of the day, the fire's rate of spread vastly exceeded what had been predicted by computer modeling, consuming in a five-hour period. A Cal Fire
public information officer described the growth as "really unprecedented in recent times, or in even veterans of our department’s recollection" for a wildfire not influenced by strong winds. The fire produced large
pyrocumulus clouds that reached in altitude, which had a tendency to collapse and spread the fire erratically when
downdrafts reached the surface. drop on August 1|leftThe Rocky Fire continued to burn actively that night and through the following day. Fire personnel abandoned the containment lines they had built on the northern/eastern flanks, retreating several miles further north to
California State Route 20 (CA 20) and further east to California State Route 16 (CA 16). There, they conducted
firing operations, burning off fuel between the highways and the fire itself so as to halt its growth in those directions. The Rocky Fire reached approximately in burned area with five percent containment by the end of Sunday, August 2. The fire burned up-slope in a drainage near
Cache Creek, creating a large plume that—in combination with a sudden wind shift—caused ember spotting up across the highway up to away in Long Valley. The fire then proceeded to burn through a subdivision, destroying multiple structures, as it moved north towards
Indian Valley Reservoir. By August 5, at roughly , the Rocky Fire's burned area was more than four times that of any other active wildfire in California, though only the portion of the fire perimeter that had burned across CA 20 remained uncontained. Despite the setback, by later in the week improved weather conditions allowed firefighters to double containment of the perimeter in two days. The fire was declared 100 percent contained on Friday, August 14. The total area burned in the fire was calculated at , According to the National Interagency Fire Center, the cost of fighting the fire came to $46.1 million at the time, or roughly equivalent to $million in when adjusted for inflation. == Cause ==