Australian Seasonal Climate Summary: Autumn 2008 (March-May)
Tuesday, 3 June 2008
Autumn 2008 was dry across most of the Australian continent. Overall temperatures were near normal over the season, with daytime maxima generally above normal and overnight minima below normal.
Area-averaged maximum temperatures were 0.83°C above normal (8th highest of 59 years), with Victoria (4th, +1.11), South Australia (5th), Western Australia (5th) and Tasmania (9th) all in the warmest ten years. Daytime temperatures were above normal over most of the country, the main exceptions being in the eastern half of Queensland (1−2°C below normal around Cairns and Cooktown), coastal New South Wales and eastern Victoria, and patches in the northern tropics. They were at least 1°C above normal over most of interior Western Australia (reaching 2−3°C above normal in many areas), South Australia except for the northeast, Victoria west of Melbourne, eastern Tasmania and western border areas of New South Wales and the Northern Territory. The South Australian coast between Ceduna and Port Lincoln (an area particularly affected by the exceptional prolonged March heatwave) had its highest mean autumn maximum temperatures on record, and a belt extending across much of the southern continent from south-eastern Western Australia to central and western Victoria was in the highest decile.
Minimum temperatures were 0.62°C below normal (10th lowest of 59 years), with Queensland’s mean autumn minima (1.93°C below normal) ranking second only to 1951, and New South Wales (−1.35) ranking 5th. Minima were above normal in most of Western Australia (except the far north) and South Australia, but below-normal almost everywhere else except the eastern parts of Victoria and Tasmania. The strongest anomalies were in a broad band extending through eastern New South Wales and Queensland, except for the coastal fringe, from Tamworth through the Darling Downs as far north as Richmond. In this region seasonal minima were 2−4°C below normal. They were also 2−4°C below normal in parts of the northern tropics, in a belt extending from the Gulf coast westwards across the Northern Territory into the Kimberley region.
Record low autumn mean minima occurred in parts of Cape York Peninsula, south-eastern Queensland, parts of southern inland Queensland extending into north-central New South Wales, the Hunter region and in places around Sydney. They were in the lowest decile in most of Queensland, the north-eastern half of New South Wales, and the northern tropics, and were only in the highest decile in the Nullabor region of Western Australia.
* Anomaly is the difference from the long-term average (1961−90)
All three months were drier than normal across the country and in every state and territory. Averaged over the continent it was the eighth-driest autumn on record (53% below normal). It also ranked in the driest ten autumns for South Australia (68% below normal, 7th), Victoria (−50%, 8th) and Queensland (−62%, 9th). The closest approaches to normal were in Tasmania (−33%) and Western Australia (−34%).
Only limited areas, mostly in Western Australia, experienced above-normal rainfall for the season. The largest of these were the south-western corner, as well as the Gascoyne and Pilbara regions, both of which benefited from tropical cyclone-related rainfalls in March and early April (a few locations around Shark Bay had their wettest autumn on record). Other areas of above-normal rainfall were the mid-north coast of New South Wales, centred on Taree, which received heavy rains in April, and the Wide Bay region of Queensland which experienced a major rain event on the last two days of May. The only other above-normal areas were scattered through the northern tropics, mostly in locations which were affected by one or more severe thunderstorms.
The rest of the continent was drier than normal and most states and territories had substantial areas in the lowest decile. Such low rainfalls were particularly extensive in much of Queensland apart from Cape York, the Northern Territory outside the Top End, interior Western Australia and the northern half of South Australia. They also covered northern inland New South Wales, and the south-eastern coast from Nowra south and west to Warrnambool, along with eastern Tasmania. Records were set locally in Queensland, including at Townsville and Mackay (a marked contrast with their extremely wet February), and numerous inland locations, such as Alice Springs and Brunette Downs (Northern Territory), and Boulia and Richmond (Queensland), had a rainless autumn.