Australian Monthly Climate Summary: June 2007
Tuesday 3rd July, 2007
June 2007 was the coldest June recorded in Australia in the post−1950 period. It was also a notably wet month in most of northern Australia, as well as along many parts of the east coast. A number of unseasonable cloudbands affected the tropics, and the month was also notable for four major east coast lows forming off the coast of New South Wales and eastern Victoria during the month, bringing heavy rain to much of the region.
Maximum temperatures were particularly low in the tropics due to the influence of increased cloud cover, with both Queensland (anomaly −3.01°C) and the Northern Territory (anomaly −3.40°C) breaking regional records by substantial margins. There was an especially exceptional cold episode from 17−22 June which saw vast areas of tropical Queensland and the NT experienced their coldest day on record, with single-digit maxima as far north as Tennant Creek (8.0°C) and Mount Isa (9.4°C). It was also unusually cold further south in Queensland with a state record low maximum for June (4.9°C) set at Applethorpe.
While anomalies were less extreme in other states, maximum temperatures were still in the lowest ten years on record in all states except Western Australia. They were below normal across the entire continent except for the western part of WA (west of a line running from Port Hedland to Kalgoorlie), where anomalies locally exceeded +1°C along the coast south of Carnarvon, and the northernmost tip of Cape York Peninsula. Anomalies below −1°C covered most of the mainland other than WA, with the few exceptions being mostly in central Victoria and the east coast between Sydney and Brisbane. An area of anomalies below −3°C (reaching −5°C at its core, near Mount Isa) stretched from the eastern Kimberley across the central Kimberley into much of inland Queensland. Records were set through most of Queensland (except Cape York Peninsula and the southeast corner), most of the Northern Territory except the Top End, northeastern SA, northwestern NSW and the north and east Kimberley in WA.
Minimum temperatures were also below normal in most areas except for the eastern third of Queensland (with anomalies locally above +1°C, particularly on Cape York Peninsula), south-eastern NSW and east Gippsland, and parts of WA centred on Geraldton and Kalgoorlie. It was at least 1°C below normal over a large area, covering north-western Victoria, western New South Wales, south-western Queensland, almost all of South Australia, the southern half of the NT, and the north and east of WA. Departures from average reached as low as −4°C near Giles (eastern WA) and north of Alice Springs. It was also 1−3°C below normal over most of Tasmania. Only a few areas saw monthly mean records set (the most significant being around Cobar and Bourke (NSW) and near the WA/NT border), but the low temperatures were consistent enough to see regional means in the lowest ten years on record in all states except Queensland.
* Anomaly is the difference from the long-term average
For rainfall it was a month of major contrasts, with above-normal totals focussed on two major areas. Most of tropical Australia, where June is normally the dry season, saw significant rainfall. This was sufficient for the area-average across the Australian tropics (north of the Tropic of Capricorn) to be the highest for June in a record dating from 1900. Site records were only set in limited areas, the most substantial being the Victoria River district of the NT, and the Richmond-Croydon area and inland from Mackay in Queensland. Vast areas had June rainfalls in the highest decile, stretching from the Kimberley across the northern two-thirds of the NT to cover most of Queensland north of a Boulia-Longreach-Dalby-Bundaberg line.
The other major area with exceptional rainfall was the coastal south-east, covering the coast and adjacent tablelands from the Hunter Valley in the north to Gippsland in the south. This area was affected by four major low pressure systems during the month, each bringing heavy rain and severe winds to parts of the region. There was substantial flooding in the Hunter Valley and in coastal areas between Sydney and Newcastle during the second week of the month, and in Gippsland (eastern Victoria) at the month’s end, whilst wind damage was also significant in some areas (notably in driving the ship Pasha Bulker aground at Nobbys Beach, Newcastle). On the positive side, the heavy rains led to a recovery in depleted water storages, especially in the Sydney area. Rainfalls in the highest decile covered most of this region. Only limited areas in the Upper Hunter (around Scone) and near Bairnsdale set June records for monthly totals, but there were still some very high totals recorded, including 644 mm at Gosford, 511 mm at Sydney, 496 mm at Newcastle and 323 mm at Bairnsdale. Mount Wellington, north-west of Sale, received 319 mm in 24 hours on the 28th, provisionally a Victorian June record and the second-highest daily fall for the state in any month. (A reported fall of 356 mm in 7 ½ hours at Mount Baw Baw on the same day is still under investigation).
Away from these regions it was a generally dry month, especially in the south-west of WA where it was the second year in a row with a very poor start to the growing season, with many areas in the lowest decile. It was also dry across Tasmania and most of SA, extending into the west of Victoria and NSW, with scattered areas in the lowest decile throughout, and a small area of record low values near Ceduna.
These contrasts saw the Australian area-average finish 53% above the 1961−90 normal (23rd highest of 108 years). Queensland had rainfall average 302% above normal (4th highest on record) and the NT 242% above (9th highest). In contrast, South Australia (64% below normal) and Tasmania (55% below, 6th lowest) were both much drier than normal, as was the southwest region of WA (47% below, 6th lowest).