Seasonal climate summary southern hemisphere (winter 2007): a developing La Niña and a positive Indian Ocean Dipole

Southern hemisphere circulation patterns and associated anomalies for the austral winter 2007 are reviewed, with emphasis given to the Pacific Basin climate indicators and Australian rainfall and temperature patterns.Winter 2007 saw the development of what would later become a La Niña event in the equatorial Pacific. This developing La Niña was associated with above average rainfall in northern Australia and eastern coastal regions over the season. Other large-scale climate drivers seemed to also play a part in rainfall overAustralia during the winter of 2007. The Southern Annular Mode was highly negative during July which may have contributed to the above average rainfall in Victoria and southwest Western Australia, and below average rainfall elsewhere. Lastly, July and especially August saw the development of cool sea-surface temperature anomalies to the northwest of Australia, associated with the positive phase of the Indian Ocean Dipole, which may have been associated with below average rainfall across much of southern Australia during August. A climatic highlight of the season was the exceptionally cold June across the country, with record low maximum and, to a lesser extent, minimum temperatures in the tropics. In terms of mean temperature it was Australia’s coldest June on record.