The fire ignited on Friday, July 31, 2020 as three separate smaller blazes within the rural canyons along Oak Glen Road before merging and rapidly expanded to 1,900 acres (769 ha) and destroyed at least one home and two outbuildings in the Cherry Valley area.

[7] Reportedly starting at 4:55 pm PST on Friday, July 31, as what was initially presumed to be two potential arson ignitions that later merged into one another, the fires started along the 9000 block of Oak Glen Road and Apple Tree Lane in the unincorporated community of Cherry Valley bordering Beaumont.

A third initially presumed arson fire had also been reported due south of the first two, which went on to burn between 60 and 80 acres as well as several unidentified buildings.

[3] The main fire proceeded to rapidly expand to 350 acres within its first two hours prompting the Riverside County Sheriff's Department to issue mandatory evacuations for well over 200 residences in the Cherry Valley area.

[9] No containment was reported throughout the day while the fire grew considerably as it burned predominantly in a north, east and southward direction towards the Banning bluff area.

By 9 pm, evacuations were extended to residents living north of Gilman Street in the Banning bluff area as the fire was by this time reportedly now 1,900 acres (769 ha) in size and remained zero percent contained.

Orders were also given to people living in the Potato Canyon west, to Raymond Flat in the Oak Glen area.

Weather-wise, high temperatures, very strong gusts, and low relative humidity all contributed to hampering firefighting efforts.

Weather -wise, officials predicted that the conditions would be warm and dry for most of the day, before cooling down a little and relative humidity increasing in the afternoon.

Weather-wise, a morning marine layer kept temperatures cooler for firefighters, but afternoon winds were predicted to pick up speed.

However, going deeper, the fire was predicted to burn into areas with dead vegetation, and also timber that had been killed by bark beetles.

By 9 pm, evacuations were extended to residents living north of Gilman Street in the Banning bluff area.

[22] CALFIRE officials stated that a diesel-fueled vehicle had emitted burning carbon from the exhaust system and into nearby brush and chaparral, according to multiple independent eyewitnesses as well as supporting physical evidence.