Seasonal climate summary southern hemisphere (autumn 2013): significant heat across Australia

Abstract

Southern hemisphere circulation patterns and associated anomalies for the austral autumn 2013 period are reviewed, with emphasis on Pacific Basin climate indicators and Australian rainfall and temperatures. Autumn 2013 saw the continuation of neutral El Niño-Southern Oscillation (ENSO) conditions that had been in place since mid-2012. ENSO indices, which include the Southern Oscillation Index, showed near neutral conditions throughout the autumn period. In the tropical Indian Ocean, warmer-than-average sea surface temperatures developed in the east, while sea surface temperatures in the western Indian Ocean cooled during the latter half of May. As a result of this pattern, the end of autumn saw the development of a negative Indian Ocean Dipole and led to above average rainfall for May, particularly across parts of southern Australia. Maximum temperatures were above average during autumn for most of Australia, with the occurrence of several heatwave events throughout the season. A heatwave event in early March saw record breaking temperatures across southeast Australia. Minimum tempera-tures were above average across most of the country, but near average across large parts of New South Wales. Averaged across the country as a whole, seasonal minimum temperatures ranked 2013 as the tenth warmest autumn in 104 years of record and seasonal maximum temperatures ranked as seventh warmest.