Weather stations were programmed to put a limit on how low temperatures could be recorded in official weather data.
Excerpts from an article by Graham Lloyd in The Australian on August 4:
“The BoM (Bureau of Meteorology) said it had taken immediate action to replace the Thredbo station (and several other stations) after concerns were raised that very low temperatures were not making it onto the official record. Controversy has dogged the bureau’s automatic weather station network since Goulburn man Lance Pigeon saw a -10.4C reading on the BoM’s website on July 2 automatically adjust to -10C, then disappear.
“BoM initially claimed the adjustments were part of its quality control procedures. But bureau chief executive Andrew Johnson later told Environment Minister Josh Frydenberg that investigations had found a number of cold-weather stations were not “fit for purpose” and would be replaced.
“It has been reported online that electronic smart cards were allegedly fitted to the BoM’s automatic weather stations, which put a limit on how low temperatures could be recorded in official weather data.
“On her website yesterday, Dr Marohasy said it was not the recording devices that were at fault. “To be clear, the problem is not with the equipment; all that needs to be done is for the smart-card readers to be removed,” Dr Marohasy said.”
Thanks to Stephen Bird, Glenn Cuthbert and Vance van Raab for this link