The Australian Bureau of Meteorology confirmed Tasmania experienced its coldest September since 2003. However, this was the only state to experience below-average mean temperature for the first month of spring. In general, the month was very warm for Australia, particularly in terms of maximum temperatures.
Tasmania had a cool September, especially early in the month when there were several days with snow to low levels. The eastern third of the State had another relatively dry month, but rain was above average in the west, BOM said.
Cold weather was dominant in Tasmania throughout the month, ensuring it was the State's coolest September since 2003. Cold outbreaks saw snowfall on the mountains several times during the month along with strong and gusty winds (including on the 30th), with snow settling to low levels from September 4 - 6, and again on the 8th and 9th.
Some sites with relatively short record had their coldest September day on record on the 4th or 5th, and kunanyi / Mount Wellington had its coldest temperature of the year on the morning of the 5th.
The main warm spells were on the 18th, and again from the 21st to the 23rd; although Tasmania escaped the heat that affected the eastern mainland, Bridport did have its highest September temperature on record on the 23rd.
The statewide mean maximum temperature was 0.74 °C (1.3 °F) below average (the coolest since 2010) and the mean minimum temperature was 0.64 °C (1.1 °F) below average (the coolest since 2003), giving a mean temperature 0.68 °C (1.2 °F) below average (the coolest since 2003).
September was also another month with below-average rain in the eastern third of Tasmania, with totals below 10 mm (0.39 inches) at some East Coast sites. Westerly winds and cold fronts meant rainfall totals were above average in the western highlands. Total rainfall for the State was about 16% above average.
Tasmania, however, was the only one to record a below-average statewide mean temperature for the first month of spring. September was a very warm month for Australia, particularly in terms of maximum temperatures (equal fifth-warmest September mean maximum temperature on record, 2.03 °C / 3.6 °F above average), BOM said.
Maximum temperatures for September were above average for Australia as a whole, with maxima in the highest 10% of historical observations (decile 10) for September across the Top End and east of the Northern Territory, the majority of Queensland and New South Wales, part of central eastern South Australia, and parts of the Kimberley and northern Interior in Western Australia. For Queensland as a whole, it was the second-warmest September on record, while New South Wales ranked sixth-warmest.
An exceptional period of unseasonably warm weather during the last week of the month resulted in many high temperature records being set in Victoria, New South Wales, and Queensland. A sequence during which surface and mid-level troughs deepened in the central Australia between slow-moving high pressure systems over the Tasman Sea and low pressure systems to the south of Australia; the result was a strong flow of warm air from central and northern Australia being drawn into eastern Australia, culminating in two distinct pulses of heat.
Many long-term stations set records for early season or monthly high maximum temperature records on the 23rd, 24th and between the 27th and end of the month. Numerous stations in New South Wales, and a few in Queensland, also set records for high overnight minimum temperatures. Some stations set new State records during the first period, which were then broken during the second pulse of hot weather. Multiple area-average temperature records were also set, including Australia's warmest September day on record on the 22nd.
State records for warmest September day were broken in each of the mainland eastern States: the new records are 37.7 °C (99.8 °F) at Mildura, Victoria, on the 23rd; 41.4 °C (106.5 °F) at Wanaaring Post Office, New South Wales, and 42.8 °C (109 °F) at Birdsville, Queensland, both on the 27th.
Nationally, minimum temperatures were above average (with an anomaly of +0.46 °C / 0.82 °F).
Featured image: Bakers Beach, Tasmania. Credit: Steven Penton
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