Australian Monthly Climate Summary: October 2008
Monday 3 November, 2008
October 2008 was warm through most of Australia, especially the south-east. It was also an exceptionally dry month in central and south-eastern Australia, ranking as the driest October on record for South Australia and in the driest three Octobers in Victoria and Tasmania.
Both daytime maximum and overnight minimum temperatures were above the long-term average over most of Australia, with maximum temperatures 1.76°C above the long-term normal (7th highest on record), and overnight minimum temperatures 1.33°C above normal (3rd highest on record).
Daytime temperatures were particularly warm, ranking in the top four Octobers for every state except Queensland and Western Australia, with Victoria setting a new record (2.73°C above normal). They were above normal everywhere except for parts of south-eastern and central Queensland and a few patches on the coasts of southern Western Australia and western Tasmania, and the bulk of the continent away from these areas was at least 1°C above normal. The largest deviations from average, typically 3−4°C, were in northern Victoria, eastern South Australia and southern inland New South Wales, although in most of those areas October 2006 was even warmer.
While the absolute difference from long-term averages was smaller than it was further south, the Top End of the Northern Territory (generally 1−2°C above normal) generally had its hottest October on record, with Darwin equalling its record for the warmest mean maximum for any month. October records were also set east of Melbourne, and around Ceduna and on Kangaroo Island in South Australia.
Overnight minimum temperatures were also above normal over most of Australia, and South Australia had its warmest October nights on record (1.91°C above normal). Minima were 2−3°C above normal in a band extending along the Tropic of Capricorn from the Pilbara region of Western Australia, through the southern Northern Territory into much of western Queensland, and were at least 1°C above normal in most of Western Australia except for the Kimberley, South Australia north of Port Augusta, the Northern Territory south of Tennant Creek, north-western New South Wales and western and far northern Queensland. Local records were set in parts of western South Australia, and in the Esperance region in Western Australia.
In contrast, overnight minimum temperatures were slightly (mostly less than 1°C) below normal in most of western and northern Victoria, extending into south-eastern South Australia, with locally damaging frosts on 23 October. Low soil moisture may have contributed to this. They were also slightly below normal in parts of eastern Queensland, and in a band across the north-central Northern Territory centred on Katherine.
* Anomaly is the difference from the long-term average
Rainfall averaged over Australia was 41% below normal for the month (25th lowest on record). It was an exceptionally dry month in much of central and south-eastern Australia. South Australia (88% below normal) had its driest October on record, Tasmania (59%) its second-driest and Victoria (77%) its third-driest. Rainfall was in the lowest decile almost throughout these three states, as well as along the western and southern borders of New South Wales. No rain fell in much of central Australia. Record low monthly totals occurred in east-central Tasmania, and in the northern Eyre Peninsula and the far south-east in South Australia. This was the second successive very dry month in these areas (and the third successive year with a very dry September-October), and year-to-date totals are also very low, with numerous locations (including Mount Isa, Alice Springs and Hobart) potentially on track for record low annual totals.
Rainfall was closer to normal (or seasonally low) in most other regions. It was quite a wet month in the south-west of Western Australia, with most areas (except the coastal strip between Perth and Bunbury) above normal. The eastern part of the region was particularly wet, with a band of falls in the highest decile (including a few record highs) extending eastwards from Merredin as far as the western Nullarbor. Rainfall was also above normal (sometimes in the highest decile) in parts of the Pilbara and Kimberley, but these areas are seasonally dry and the totals involved were small (mostly below 25 mm). Other above-normal areas included parts of the northern NT Top End favoured by early-season storms, northern Cape York Peninsula and the coast around Cairns in Queensland, and parts of southern inland Queensland and north-eastern NSW, but only a few locations reached the highest decile.