I don’t currently have live tool access in this turn to verify the latest details, but I can summarize what is known about the Tongariro National Park fire and how it started based on recent reporting up to late 2025. Direct answer

• As of the most recent updates, the exact cause of the Tongariro National Park fire had not been established. Investigators from Fire and Emergency New Zealand (FENZ) were deployed to examine potential ignition sources, including human activity and natural causes, but no definitive conclusion had been announced in the public briefings available at that time.

Context and what’s been reported

• The fire began on the Central Plateau, with large-scale evacuations of trampers and nearby residents, and significant challenges for firefighting efforts due to wind and terrain. Authorities described it as an uncontrolled vegetation fire that expanded rapidly over hundreds to thousands of hectares. Investigations were described as ongoing, with a specialist wildfire investigator assisting police in determining the ignition source.

• Local updates indicated the fire’s cause remained unknown for days after it started, and responders emphasized careful analysis to distinguish between accidental human causes (for example, discarded cigarettes, campfires, or vehicle-related incidents) and natural ignition possibilities (such as lightning), though no definitive finding was published in those early reports.

• Ongoing coverage highlighted that conditions on the ground—strong winds, dry vegetation, and varied topography—played a critical role in the fire’s rapid spread, complicating both detection and attribution of the ignition source. Evacuations and safety measures remained the immediate priority while investigators pursued the root cause.

Notes

• Multiple outlets reported that an official cause had not yet been determined and that a specialist wildfire investigator would assist in the inquiry, underscoring that the investigation was active and preliminary at the time of those reports.

• For the most up-to-date determination of the ignition source, checking the latest official Fire and Emergency NZ updates or DoC statements would provide the final conclusion of the investigation.

If you’d like, I can search for the very latest official statements or provide a timeline of the fire’s progression and containment status from credible sources.