Lieutenant William Bradley’s weather journal

H.M.S. Sirius Weathering Tasman's-Head, by George Raper, 1791. Image: State Library of NSW

Another vital early weather resource is the record of William Bradley’s daily noon temperature recorded in a weather journal kept on the HMS Sirius. The temperature record was maintained during the First Fleet’s voyage (1787–1788) and while the vessel was anchored in Botany Bay (20–26 January 1788) and Port Jackson (27 January–13 September 1788).

Bradley’s temperature record over the course of the voyage can be seen in this Google Earth animation.

The records of Dawes and Bradley are remarkable in that they appear comparable with modern day measurements taken from Sydney Observatory Hill.

The weather journals display similar daily variability, a distinct seasonal cycle and considerable inter-annual variability.