As Fairfax reported, new research by the ARC Centre of Climate System Science shows how days of heat extreme heat since 2000 now outnumber cold ones by a ratio of 12 to one.

Taking the past 15 years as a single period, almost all of the country has had above-average to highest-on-record temperatures compared with any other 15-year stretch, according to the Bureau of Meteorology.

The rainfall over the 2000-14 period helps to explain why much of the Northern Territory missed out on the warmer temperatures.

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As shown below, the middle third of Australia - where relatively few people live - has been wetter than most other rolling 15-year periods:

The extra moisture means more evaporative cooling, and hence the milder temperatures over parts of the interior, one climatologist said.

Perhaps of more impact has been the record-low rainfall along the western edge of the country, which is also showing up in a sharp drop in water run-off into reservoirs in that region.

Similarly of note is the relatively dry period for most of Victoria and Tasmania. It's a trend that continues to play out in 2015, with parts of western Victoria experiencing their driest 12 months on record.