Bureau of Meteorology Rejects Claims of Widespread Errors in Climate Dataset

Australia’s Bureau of Meteorology (BoM) has strongly rejected recent claims that its primary long-term temperature dataset contains widespread errors or intentional manipulation. The response follows a media campaign published by The Australian newspaper, which highlighted a privately produced audit criticizing the agency's record-keeping integrity.

Understanding the Controversy and the Data

The discussion centers on the Australian Climate Observations Reference Network – Surface Air Temperature (ACORN-SAT) dataset, which draws observations from 112 weather stations across the country. The BoM applies a rigorous quality control process to this network to account for local changes, such as station relocations, that could otherwise distort long-term climate trend analysis.

Over the past week, media coverage championed an unofficial "audit" conducted by a retired scientist and a former computer engineer. The report alleged various anomalies, including missing or duplicated data entries and patterns it argued were statistically improbable.

The Bureau's Response

The bureau released a formal statement addressing the specific technical points raised in the audit, dismissing accusations of deliberate or fraudulent human intervention as false and unsubstantiated.

Regarding the claim of duplicated records, the bureau acknowledged that a very small number of historical observations—fewer than 200 out of millions—contained duplications linked to manual digitisation of handwritten records dating back before 1946. According to the BoM, the resulting impact on the long-term temperature record is statistically irrelevant, and no further duplicate months have been found across the broader network. Officials indicated that the errors likely stemmed from manual handling when records were transferred to punch-card systems in the mid-20th century.

On the matter of repeated temperature sequences—such as consecutive days of identical maximum temperatures recorded at Palmerville in 2004—the bureau explained that the audit failed to account for historical observation practices where temperatures were recorded to the nearest whole degree, a factor that, combined with low temperature variability in tropical regions, makes repeated values more likely.

Practical Implications and Verification

For readers seeking to understand how official weather data is managed and scrutinized, several facts and distinctions are worth noting:

• Confirmed vs. Unknown: It is confirmed that minor, isolated historical data duplications occurred during mid-century digitisation processes; however, the bureau confirms their statistical impact on modern climate modeling is negligible. The precise human error behind the 1950s/1960s punch-card transcription remains a working hypothesis.
• Transparency: The ACORN-SAT dataset relies on publicly available raw weather station data. The methodology used by the bureau has previously undergone independent reviews and has been published in peer-reviewed scientific literature.
• How to Verify: Readers can review the official background and statements directly through [The Guardian's original report](https://www.theguardian.com/environment/2026/oct/25/bom-temperature-record-keeping-under-attack-again) or access public datasets and explanatory notes directly via the [Bureau of Meteorology website](http://www.bom.gov.au).