Dixie Fire 2021: Cause, Timeline & Evidence

Incident snapshot

• Location: Feather River Canyon above Cresta Dam; CAL FIRE incident-page coordinates 39.871306, -121.389439. The later CPUC investigation gives a more specific ignition-area coordinate, 39.874608, -121.378855. The two fields describe different levels of location precision.
• Incident start field: July 13, 2021 at 5:15 p.m. on the CAL FIRE incident page. Investigators later reconstructed an earlier tree-to-line contact; these timestamps must not be treated as equivalent.
• Final mapped size: 963,309 acres in Butte, Plumas, Shasta, Lassen and Tehama counties, according to the CAL FIRE incident header and its January 2022 release.
• Containment: the CAL FIRE incident page records October 25, 2021 at 7:45 a.m.; the National Park Service timeline says October 26. See the source-conflict note below.
• Human toll: the CAL FIRE incident page lists one confirmed firefighter fatality. Do not infer civilian fatality totals from an empty field.

Fire DNA: origin, spread and exposure

Origin finding

On January 4, 2022, CAL FIRE announced that a tree contacted PG&E electrical distribution lines west of Cresta Dam and caused the Dixie Fire. This is a later investigative finding, not a claim that the precise mechanism was known to the public when the fire started.

The California Public Utilities Commission Safety and Enforcement Division (CPUC SED) report, dated October 9, 2023, describes the sequence in greater detail, citing the CAL FIRE investigation: a damaged Douglas fir fell onto the Bucks Creek 1101 circuit; two fuses opened, but one conductor remained energized in contact with the tree. The report attributes subsequent heating and ignition of receptive ground fuel to a high-impedance fault over several hours. This is the investigation’s reconstruction, not a real-time observation of every moment of ignition. The SED report lists findings about PG&E’s compliance with utility rules; those are regulatory findings and should not be converted into an unqualified claim about a court judgment.

Propagation evidence

NASA’s June 2022 Scientific Visualization Studio reconstruction uses VIIRS satellite active-fire detections to show the changing fire front approximately every 12 hours from July 14 through October 22, 2021. It identifies rapid expansions, spot fires outside the main perimeter and detections behind the active edge. Satellite detections and their derived burned-area estimates are a separate measurement stream from CAL FIRE’s incident acreage; neither is a parcel-by-parcel record of structure ignition.

Protected-area and community exposure

The National Park Service records Dixie entering Lassen Volcanic National Park on August 5 and a final footprint of 73,240 acres within the park by September 30. This park acreage is a subset of the overall incident footprint, not an amount to add to 963,309 acres. Its timeline documents closures, evacuation warnings and confirmed park-structure losses on specific dates. Those observations do not establish the ignition mechanism of each individual building.

Known At / Evolution of Knowledge

1. July 13, 2021 — incident: CAL FIRE records the operational start at 5:15 p.m. near Cresta Dam. Later investigative materials reconstruct tree-to-line contact earlier that day. Preserve both timestamp meanings.
2. August 24, 2021 — operational snapshot: a CAL FIRE incident update reported 731,310 acres and 41% containment, with the cause still under investigation. That snapshot must remain dated; it is not the final extent.
3. September 8–10, 2021 — operational snapshots: CAL FIRE update pages reported 922,192 and then 950,591 acres, respectively, while cause remained under investigation. These values show evolving estimates, not a continuous hourly perimeter.
4. October 2021 — containment: the CAL FIRE database records October 25; NPS lists October 26. Both sources agree on the final size of 963,309 acres.
5. January 4, 2022 — origin finding: CAL FIRE publicly attributed the fire to a tree contacting PG&E distribution lines west of Cresta Dam.
6. June 1, 2022 — reconstructed spread: NASA published its satellite-based time series; this retrospective model must not be described as the live information available to responders in July.
7. October 9, 2023 — regulatory reconstruction: CPUC SED published a report detailing the electrical fault sequence and its rule-compliance findings.

Evidence reconciliation: do the numbers agree?

Structures: CAL FIRE’s current incident-page damage panel displays 1,311 destroyed and 94 damaged; CAL FIRE’s January 4, 2022 cause release reports 1,329 destroyed and 95 damaged. The CPUC SED report repeats the 1,311/94 series. The source documents do not explain this discrepancy in the excerpts used here. Keep each pair attached to its source and do not average or silently prefer one.

Area: the incident header and cause release agree on 963,309 acres. An old West Zone situation-summary paragraph embedded in the same CAL FIRE incident page still says 963,276 acres and 94% containment. That paragraph describes an earlier operational state; it must not replace the final header.

Containment date: CAL FIRE lists October 25, 2021 at 7:45 a.m., while NPS says October 26. The available source text does not resolve whether reporting conventions or update timing explain the one-day difference.

Cause field: CAL FIRE’s incident-page metadata still says “Under Investigation,” although the agency’s separate January 2022 news release publicly states an investigated cause. Present the dated release and flag the stale field instead of treating the metadata as a reversal of the finding.

What the evidence supports

This case connects a documented electrical origin to a long-duration, multi-county fire and a separately reconstructed sequence of spread. It does not support calculating a single rate of spread for the full 963,309 acres, inferring the exact arrival time at a property from a 12-hour satellite animation, or claiming that a specific home-hardening action would have saved an identified structure. Such claims require finer incident and parcel evidence.

Source ledger

1. CAL FIRE, Dixie Fire incident record — header, operational metadata, damage panel and legacy situation summary; last updated October 14, 2022.
2. CAL FIRE, Dixie Fire cause news release, January 4, 2022 — investigated origin and its own damage counts.
3. CPUC Safety and Enforcement Division, Dixie Fire Investigation Report, October 9, 2023 — electrical sequence, evidence inventory and regulatory findings.
4. NASA Scientific Visualization Studio, Spread of the Dixie Fire — 2021, June 1, 2022 — VIIRS-derived 12-hour retrospective fire tracking and its limitations.
5. National Park Service, Dixie Fire timeline — park dates, footprint and containment reporting.
6. CAL FIRE, August 24, 2021 incident update and September 8 update and September 10 update — dated operational snapshots.