Australian Seasonal Climate Summary: Summer 2006/07 (December-February)
Tuesday 6th March, 2007
Rainfall over Australia was widely near normal during the summer of 2006/07, after the very dry conditions which prevailed through most of the second half of 2006. Temperatures were mostly above normal, with a very warm February in most areas following near-normal conditions in December and January.
Generally very warm conditions in February lifted summer temperatures above normal after cooler conditions in December and January. Both mean maximum temperatures (0.57°C above the 1961−90 normal) and minimum temperatures (0.56°C above normal) were the 10th highest on record.
Maximum temperatures were particularly warm in most of Victoria, northern and central Tasmania, the southern and central ranges in New South Wales, the southern half of South Australia, and a band running across Western Australia from the Pilbara to the Nullarbor. Most of this region was at least 1°C above normal (locally 2°C above average in central Victoria and between Canberra and Bathurst), and records were set locally in north-eastern Tasmania and around the Western Australia/South Australia border.
In contrast, maximum temperatures were below normal in most of Queensland (except the southern inland and Cape York Peninsula), although anomalies only locally reached −1°C. Cool conditions also prevailed along the coastal fringe of Western Australia between Carnarvon and Perth in areas strongly influenced by sea breezes. The highest individual temperature of the summer was 48.6°C at Hyden (WA) on 3 February, one of the highest temperatures ever recorded so far south (32°S) in Australia.
Most of the continent experienced above-normal minimum temperatures, and anomalies were above +1°C over eastern Western Australia, most of South Australia, much of inland New South Wales and southern Queensland, and northern Tasmania. No significant records were set. The only major areas where minima were below normal were western parts of Western Australia, the eastern coastal fringe between Sydney and Townsville, and a band running east-west through northern Queensland from Townsville to Mount Isa.
* Anomaly is the difference from the long-term average
The area-averaged rainfall over Australia was 6% below normal (47th lowest of 107 years), with all states and territories within 20% of normal except for New South Wales (30% below), and relatively few areas with rainfall in either the highest or lowest decile.
The main areas which were in the wettest decile (top 10% of all summers) were in the Esperance-Kalgoorlie area of Western Australia, the Flinders Ranges in South Australia, the far south-west of Queensland and adjacent parts of the Northern Territory, and a small area along the western border of the Northern Territory. These are all areas which are normally dry in summer and received most of their 2006−07 rain in one major event. Some locations received more rain in one or two days than they received in all of 2006, the most notable being Bedourie in western Queensland, where 169.1 mm on 21 January compared with 53 mm in all of 2006 (and also exceeded the long-term annual average).
Areas in the driest decile were also limited, with the most significant being in the western Pilbara in Western Australia, the Darling Downs of south-eastern Queensland, and parts of central Victoria. Rainfall was somewhat below normal over most of the Murray-Darling Basin, limiting any recovery from the severe 2006 drought for the time being. The very dry conditions were a major contributing factor to numerous major and long-lived bushfires, especially in the mountains of eastern Victoria, where lightning on 1 December ignited fires which merged into a single blaze which remained uncontained until early February; approximately 11,000 square kilometres were burned.
Tropical cyclone activity during the summer was very much below normal. Only one cyclone had formed in the Australian region by the end of February (a second, Isobel, was named but found not to have reached tropical cyclone intensity on later analysis), the first time since at least 1944−45that there has been so little activity by the end of summer.