The Bureau of Meteorology is aware of a report produced by a member of the public regarding Australia’s long-term temperature record, which claims to show evidence of “manual data manipulation”. These claims are false and unsubstantiated.
The claims in the report are based on several misunderstandings, among them: the nature and precision of historical temperature records, how they were recorded and are managed; lower variability of temperature in places such as the tropics which make repeated patterns in raw data more likely; how the bureau’s ACORN-SAT homogenisation and cumulative adjustments operate.
The bureau takes its stewardship of this important national data set seriously. We have conducted analysis of all underlying data examined in the report, which confirmed a small number of duplicated historical daily temperatures. These were 4 post-1910 months relevant to the Australian Climate Observations Reference Network – Surface Air Temperature (ACORN-SAT).
These account for fewer than 200 daily values from a dataset containing more than 7 million values. They are all from handwritten records of pre-1946 data that have been manually digitised. The resultant impact on Australia’s long-term temperature record is so small as to be statistically irrelevant. We have corrected these values in this year’s update, completed on 19 October 2026.
Further investigation has detected no further duplicate months in the entire bureau network other than those quoted in the report and then confirmed by us. Historical climate records were digitised using methods including punch-card systems in the 1960s, which may have contributed to isolated transcription errors. The bureau is confirming if it was the cause in this case. We can confirm that this has no impact on the climate record.
The bureau rejects allegations of fraudulent or deliberate manipulation of Australia’s temperature record – there is no evidence to support this assertion, and it has no basis in fact. Our data stands up to consistent, stringent scientific and public scrutiny, and has done over decades.
The bureau works continuously to maintain the integrity, quality and transparency of Australia’s meteorological and climate datasets. This includes the long-term management of historical observation records, ongoing quality assurance processes, and the continued publication of data, methodologies and supporting documentation to enable public access and independent examination.
The history of recording Australian weather observations dates back to within months of the First Fleet. However, it wasn’t until 1910 and the formation of the Australian Bureau of Meteorology that standardised equipment was established in many parts of the country, with further expansion since then.
Ensuring Australia has a modern and consistent temperature record requires scientific understanding and a lot of work. Some of this requires digitising records from last century- often painstaking manual data entry from paper-based records to electronic databases. Other tasks require scientific knowledge, such as understanding the impact of technology changes on the consistency of the data over time.
The bureau’s climate data experts have carefully analysed the digitised data to create a consistent-or homogeneous-record of daily temperatures spanning more than 100 years.
The ACORN-SAT homogenised temperature database comprises 112 carefully chosen locations that maximise both length of record and network coverage across the continent.
The integrity of ACORN-SAT and its methods have been published in scientific literature and independently reviewed in 2011, 2015 and 2017, with those reviews expressing overall confidence in the bureau’s practices and method, the development and operation of ACORN-SAT and considering its practices as among the best in the world, offering continued support for the bureau’s approach to homogenisation.
The bureau does not overwrite or delete original temperature observations when producing ACORN-SAT. Original observations are retained separately, quality issues are recorded, and ACORN-SAT is produced as an additional analysed dataset. Both original and homogenised data are made available for external scrutiny. The bureau makes the underlying observational data publicly available.
The bureau is aware of commentary aired in the media regarding this topic, singling out bureau staff. While we respect that as an essential public institution, our work and information should be open to scrutiny, the bureau has zero tolerance for our people being individually targeted.
