Australian Seasonal Climate Summary: Winter 2007 (June-August)
Wednesday 5th September, 2006
Both temperatures and rainfall averaged across Australia in winter 2007 were very close to normal, but there were some wide regional variations. It was an abnormally wet and cool season through much of tropical Australia and a very wet one along most of the east coast, but many other parts of the continent were warm or dry or both. Rainfall was 2% below the 1961−90 normal, while the national mean temperature anomaly for winter was −0.11°C, making it the coolest winter since 1997.
It was a rather cool winter in the tropics, with both daytime maxima and overnight minima generally below normal. Maxima were 2°C or more below normal in a belt extending across the continent from the east Kimberley through Tennant Creek to around Charters Towers. Winter mean maxima were in the lowest decile through most of the northern tropics except for Cape York Peninsula and the northern Top End of the NT, and were at record low levels in parts of the east Kimberley and north-western Queensland. Overnight minima were also below normal in the tropical parts of the NT and WA, although less so in Queensland. Some areas in the Kimberley and on either side of the WA/NT border were 2 to 3°C below normal. Mean winter maxima were the 4th lowest on record in Queensland (anomaly −0.95°C), and minima the 7th lowest on record in the NT (−1.16°C).
It was a very mild winter in the southern half of WA, both by day and night. Maximum temperature anomalies of +1 to +2°C (exceeding +2°C east of Geraldton) were widespread through the region except for the far southwest, whilst minima were generally close to 1°C above normal. Most of the region (along with western parts of SA as far east as Port Lincoln) had maxima in the highest decile, and minima were also in the highest decile in many areas, with records set in some areas, notably around Kalgoorlie. No station in Western Australia recorded a daily maximum below 11°C during winter, an event unprecedented in the historic record.
Winter minimum temperatures were generally reasonably close to normal in most of the southeast, although minima were rather warm (anomalies around +1°C) along the east coast and adjacent ranges. Conversely, they were rather cool in northwestern Victoria and the Eyre Peninsula, with a number of locations in the lowest decile. Maxima were slightly above normal over most areas away from the east coast, grading to slightly below normal on the coast itself.
* Anomaly is the difference from the long-term average
Winter rainfall was above normal in most of Queensland, the northern half of the NT, and the Kimberley region of WA. Most areas north of a line from Derby to Tennant Creek to Rockhampton had rainfall in the highest decile, and parts of the northern inland of Queensland and the north-central Northern Territory had their wettest winter. In a region where any amount of winter rain is unusual, the most significant falls occurred in June (which was the wettest on record for tropical Australia), but unseasonable rain events also affected parts of the region in August. The winter rainfall in Queensland and the NT were 87% and 59% above normal respectively.
Above-normal rain also extended south along the east coast and adjacent ranges from southern Queensland through NSW to eastern Victoria. June was also the wettest month in this region as a whole, with several major east coast lows and associated flooding, but August also saw a number of major coastal rain events, including a fall of 713 mm in 24 hours at Rainbow Beach (Queensland), the highest daily fall recorded in Australia in winter. Only a few locations set seasonal records, but readings in the highest decile were widespread in the Sunshine Coast/Wide Bay area north of Brisbane, the eastern two-thirds of Gippsland, and the Sydney and Hunter regions in NSW.
In south-eastern Australia the wet conditions were largely confined to the east coast. It was a rather dry winter in inland NSW and northern Victoria, and a very dry one in much of South Australia, where readings in the lowest decile were commonplace in the agricultural areas and areas around Ceduna had their driest winter on record. The state-wide mean (62% below normal) was the fourth-lowest on record. It was also dry in much of central WA. In the south-west of WA, southern Victoria (except Gippsland) and Tasmania, winter rainfall was generally near- to slightly below-normal.