Australian Monthly Climate Summary: May 2009
Monday, 1 June, 2009
May was a dry month through much of Australia. Except for parts of the east coast, which experienced a major storm in the second half of the month with significant flooding and coastal erosion, rainfall was below average over most of the continent. Both daytime and overnight temperatures were fairly close to normal.
Daytime maximum temperatures were very close to average (0.08°C above normal, 30th lowest of 60 years). They were well above average on the west coast and adjacent inland of Western Australia, where anomalies were mostly +2−3°C south of Shark Bay. These temperatures were in the highest decile, with records set in the Geraldton area. Less substantial positive anomalies, peaking at +1−2°C in northern Victoria and southern inland NSW, were found in much of eastern Australia (including Tasmania) south of the tropics, as well as in the Top End of the Northern Territory. Elsewhere, maximum were 1°C or more below normal in large parts of central Australia, with anomalies of −2−3°C near the SA-NT border.
Overnight minimum temperatures were 0.33°C below normal (24th lowest of 60 years). They were warmer than normal in scattered parts of the southeast, including most of Tasmania, eastern NSW, eastern and western Victoria, eastern South Australia and far southwest Queensland, as well as near the Gulf of Carpentaria in Queensland and the northwest Top End. Only a few places were as far as 1°C above normal.
Over most of the remainder of the country, including much of central and western Australia, minimum temperatures were below normal, but anomalies were generally reasonably small, only locally reaching −1°C. The most significant cool anomalies were in Western Australia in three separate areas centred on Carnarvon, Albany and Giles, all of which were in the lowest decile.
* Anomaly is the difference from the long-term average
Rainfall averaged over Australia was 42% below normal (32nd lowest of 110 years). It was below normal for all states and territories (ranging from 17% below normal for New South Wales and the Northern Territory to 64% below in Western Australia and 60% below in Victoria), although no state ranked in the driest 10 years on record.
The major area of above-average rainfall was along the east coast in northern New South Wales and southern Queensland, extending from the Sydney area to Bundaberg, with falls in the highest decile extending from Port Macquarie to Brisbane. The Mid-North Coast region of NSW was especially wet, with Dorrigo receiving 934 millimetres for the month, including 409 on 22 May, the second-highest daily fall on record for May in NSW. Above-average rainfalls also extended into southern inland Queensland east of Roma and St. George (with an area in the highest decile centred on Goondiwindi), and parts of northern inland NSW between Nyngan and Bourke.
Other above-average areas covered much of the southern Northern Territory and adjacent border areas of South Australia and Western Australia (although totals were light, only locally reaching 25 millimetres), southwestern Tasmania, and parts of the far northern tropics, including northern Cape York Peninsula (north of Weipa) and north-eastern Arnhem Land in the Northern Territory.
Areas with rainfall in the lowest decile were scattered through the southern states, the largest being in Western Australia where they covered most of the southern coast and southeastern interior. There were also areas in the lowest decile around and east of Melbourne, northeastern Tasmania, the South-West Slopes region of NSW between Wagga Wagga and Canberra, and the western coast of the Eyre Peninsula in South Australia.
* A new area-averaging method has been adopted for rainfall from May 2009. Current and historical totals for Tasmania are substantially higher than under the old scheme, but differences for other states, and nationally, are negligible.