Seasonal climate summary southern hemisphere (summer 2009–2010): an El Niño summer; wetter than average for east, north and central areas, dry in Western Australia and Tasmania

Abstract

Southern hemisphere circulation patterns and associated anomalies for the austral summer 2009–2010 are reviewed, with emphasis given to the Pacific Basin climate indicators and Australian rainfall and temperature patterns. Summer 2009–2010 saw the mature phase of an El Niño event and the beginning of its decline. Despite the El Niño the season was one of contrast—particularly wet for most of northern-central, eastern and northern Australia away from Cape York, southern South Australia, Victoria and the central east coast, yet dry over most of Western Australia and Tasmania. Australia’s summer rainfall was twenty three per cent above normal in 2009–2010 and eight of the last eleven summers have ranked in the wettest 20 of the last 110 years. Summer was also generally warmer than normal with maximum temperature anomalies similar in pattern to rainfall anomalies; large areas of Western Australia around the inland Pilbara and in the southwest recorded record high temperatures, while nearly all of Victoria and Tasmania, as well as southern South Australia, were in the highest decile. Seasonal minimum temperatures were warmer than average for most of the country except far southwest Western Australia and the northwest coast, northern central Australia and inland Queensland, with areas of Western Australia’s interior recording record warm nights. Combined with an extremely warm winter and spring, summer 2009–2010 marked Australia’s warmest nine months on record.