Issued on 7 August 2009
Long-term rainfall deficiencies persist; some relief to short-term deficits over parts of southern Australia
Parts of southern Australia recorded above average rainfall during July 2009, particularly near the coast. Elsewhere, rainfall was generally below the long-term mean, with large areas of Queensland experiencing very much below average rainfall. Average to above average July rainfall over western Victoria and southeast SA has relieved most of the short-term deficits that existed in the 6-month period ending June 2009. However, longer-term deficits remain in these regions.
Rainfall deficiency maps for standard periods out to three years are available here.
7-month rainfall deficiencies
For the 7-month period from January to July 2009, serious to severe rainfall deficiencies remain evident over most of central and eastern Victoria. A few very isolated areas of serious to severe deficiencies also remain evident across central Australia and along the far south coast of NSW. Victoria has now experienced its fourth direst January to July period on record, with several stations near Melbourne and in Gippsland recording lowest on record rainfall for the period. However, as mentioned in the introduction, good July rainfall over western Victoria and southeast SA has relieved most of the short-term rainfall deficits that existed in the 6-month period ending June 2009.
24-month rainfall deficiencies
For the 24-month period from August 2007 to July 2009, serious to severe rainfall deficiencies remain evident across much of southeast Australia and parts of central Australia. These regions experienced some average to above average rainfall during the final months of both 2007 and 2008, as well as through the most recent autumn. However, most months through the period were drier than the long-term mean, especially during the growing seasons. Both 2007 and 2008 were classified as positive Indian Ocean Dipole (IOD) years, which is likely to have contributed partly to the low winter and spring rainfall recorded across parts of southern Australia during both these years.
Very long-term rainfall deficiencies outside of the drought periods discussed above persist across parts of southern and eastern Australia. Most notably, rainfall has been below average across much of southwest and southeast Australia since 1997, while the Murray-Darling Basin has experienced below average rainfall since 2002.
Lowest on record - lowest in the historical analysis, which runs from 1900.
Severe deficiency - rainfalls in the lowest 5% of historical totals.
Serious deficiency - rainfalls in the lowest 10% of historical totals, but not in the lowest 5%.
Very much below average - rainfalls in the lowest 10% of historical totals.
Below average - rainfalls in the lowest 30% of historical totals, but not in the lowest 10%.
Average - rainfalls in the middle 40% of historical totals.
Above average - rainfalls in the highest 30% of historical totals, but not in the highest 10%.
Very much above average - rainfalls in the highest 10% of historical totals.
Product Code IDCKGD0AR0