Australia's year of extreme weather has collected a fresh record with January posting the hottest average temperatures for the month on record.
With just a day's data to be collected, the average of maximum and minimum temperatures for the month was 29.7 degrees. That tally was 1.79 degrees above the long-term average.
Short of a remarkably frigid final few hours for the month, January was all but certain to beat the previous record set in 1932, the weather bureau said.
The monthly result means the September-January period was also the hottest on record, beating the previous three highest in 2002-03, 2006-07 and 2009-10.
Those earlier years "were all El Nino and drought years, whereas that hasn't been a factor this time," said Blair Trewin, senior climatologist with the bureau's national climate centre. "That makes it even more remarkable."
Trewin said that while Australia had a variable climate, the recent heat spell should be seen against the backdrop of longer-term warming.
"If you do super-impose your normal variability on a warming background trend, you are going to see more warm extremes and fewer cold extremes," he said.
The rainfall tallies show a mixed picture, with some regions along the east coast reporting well-above average rain, thanks mostly to the remnants of tropical cyclone Oswald, which dumped record rain on many parts of Queensland and New South Wales.
By contrast, parts of Victoria posted record low rainfall for the month, particularly in the south west, Trewin said.
Melbourne's tally of eight millimetres - about one-sixth of the city's average - placed it within the driest 10 per cent of annual records dating back to 1855.
Sydney's Observatory Hill collected 138 millimetres of rain in January - most of it falling in the 24 hours to Tuesday morning - or about one-third more than the average for the month, said Brett Dutschke, senior meteorologist at Weatherzone.
The massive heatwave in the first half of the month prompted the bureau to add extra colours to its heat charts in case temperatures climbed above 50 degrees Celsius.
While the new colour scheme of purples and pinks for 50-52C and 52-54C has yet to be used, the country did smash previous records dating back to 1910 for days in a row of average maximums above 39C (seven) and the hottest area-average mean temperature at 32.36C.
One of the month's more notable records was Alice Springs, which notched up 17 days in a row over 40C.
In 1972-73, the previous time Australia experienced such a broad-based heatwave, the town managed 17 days straight over 39.5C, Trewin said.
While the big wet brought cooler temperatures in some east coast regions towards the end of the month, unusual wind patterns triggered hotter-than-usual weather to north Queensland. Cairns, for instance, saw the mercury climb to 38.6C on Tuesday, its hottest day since 1995.
- Sydney Morning Herald
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