Australian Monthly Climate Summary: September 2008
Wednesday 1 October, 2008
September was a warm month almost throughout Australia. Both daytime maximum and overnight minimum temperatures were well above normal through most of the continent, although few records were broken. It was wetter than normal through large parts of northern Australia (which is normally dry at this time of year), but dry through much of the south.
National daytime maximum temperatures were 1.47°C above the long-term (1961−90) average, the ninth-highest value on record. (This is the 15th consecutive September with above-average maximum temperatures, with 13 of those 15 years being at least 0.8°C above average). Maxima were above normal almost throughout the continent, with only a few areas cooler than average (mostly in northwestern Tasmania, the central coast of Queensland, and some areas north of Perth). Most areas outside of Queensland, Tasmania and the south-west of Western Australia were at least 1°C above normal, while temperatures 2−4°C above normal covered much of western New South Wales, parts of central South Australia, the southern Northern Territory, and areas around Broome (where some records were broken).
Overnight minimum temperatures were only slightly closer to average, being 1.29°C above average (8th highest on record). Nights were cool in parts of the south where rainfall was low, including Victoria (except the far east), Tasmania, the southern half of South Australia, and parts of western Western Australia, with anomalies around −1°C enough to place the minima in the lowest decile in parts of the Wimmera (Victoria) and Riverland (South Australia). However, most of the northern half of Australia (north of a Carnarvon-Giles-Broken Hill-Coffs Harbour line) had minima at least 1°C above normal, reaching 2−3°C above normal in most of the southern half of Queensland and the Northern Territory, as well as the west Kimberley region in WA.
* Anomaly is the difference from the long-term average
Rainfall averaged over the continent as a whole was slightly above normal (6% above average, 33rd highest of 109 years). Much of northern Australia was wetter than average, although, September being well into the dry season, the actual totals involved were modest – only in the southern half, and on the north tropical coast, of Queensland did totals exceed 50 millimetres. These totals were sufficient to place the September rainfall in the highest decile through much of central Queensland, and in an area extending from the north-east of Western Australia across the central Northern Territory. Other wet areas were the north-east quarter of New South Wales, especially the Mid-North Coast and Hunter regions, and parts of the south-west of Western Australia, especially the northern wheatbelt and southern Goldfields regions (with record monthly totals around Norseman). In the latter case most of the rain fell in a single event during the last week of the month.
In contrast, it was a dry month in South Australia and Victoria (extending into the southern fringe of New South Wales and the south-east of Western Australia). Both states had their eighth-driest September on record (76% and 51% below average respectively), with Victoria having its driest September since 1972. Falls in the lowest decile occurred widely in central and northern Victoria, and the Eyre Peninsula and Mid-North regions of South Australia, and it was the driest September on record at a number of significant centres, including Melbourne, Sale and Mildura. This month continued dry years for both states. South Australia’s January-September rainfall (52% below average) is the fifth-lowest on record and lowest since 1959, while Victoria’s (30% below average) is the eighth-lowest on record.