It will come as no surprise that the data is in and 2019 has topped the Bureau of Meteorology’s (BoM) charts for average and maximum temperatures as well as the lowest annual rainfall across the country.
Those suffering through the current horror fire and heatwave season will not be surprised that the conditions leading up to it were the worst on record.
The new figures arrived as large parts of the country braced for more dangerous fire conditions over the next few days.
ABC News reports that BoM will comment when its official report comes out next week, but the numbers speak for themselves.
Australia’s annual mean temperature was 1.52 degrees Celsius above the 1961-90 average of 21.8°C, well above the previous hottest year (2013) at 1.33°C.
Also, the daytime temperature record was smashed, with the average maximum temperature of 30.69°C coming in 2.09°C above the 1961-90 average.
The previous record, set in 2013, was 30.19°C.
Overnight temperatures did not surpass the record, but they were still the sixth hottest on record and well above average at 0.95°C above the 15.1°C 1961-90 average.
Meanwhile the drought has dragged on.
The national average rainfall total for the year was 277.63 millimetres, well below the previous record of 314.46mm in 1902 during the federation drought.
ABC News report the 1961-90 period is an internationally used standard as a period of good weather records used for data comparisons.
These values are calculated based upon gridded data from across Australia.
The country is broken up into a 0.05-degree grid by longitude and latitude, which is roughly 5km by 5km, with each grid assigned a maximum temperature based on the weather stations around it.
The average of all of the grids for every day of the year is then output.
Using the same gridded dataset, Australia broke the record for its hottest day on record two days in a row last month, the nation’s average maximum temperature smashing the previous record (40.3°C) to reach 40.7°C and then 41.9°C a day later.
ABC News reports the record-breaking year was especially noteworthy because it occurred without an El Nino event, the climate driver most commonly associated with hot dry conditions in Australia.
While the Pacific Ocean remained neutral, the main climate driver was the incredibly strong positive Indian Ocean Dipole (IOD).
The IOD has been working to generate rising air and rain over eastern Africa but hot descending air over Australia.
It is associated with drought and hot conditions over eastern Australia as well as with a delayed monsoon, all of which have been the case this summer.
Late last year, an unusual sudden stratospheric warning (SSW) event also added to the hot dry conditions by shifting the westerly winds, which usually lurk over the Southern Ocean, up onto the continent.
This event was also associated with a strong positive phase of the Southern Annular Mode (SAM),again encouraging hot dry conditions.
ABC News reports this is all on top of the anthropogenic global warming trend; BOM records show Australia has warmed by just over a degree since 1910, with most of the warming occurring since 1950.
Thankfully the positive IOD and negative SAM have decayed and the BOM’s outlook for the next three months is decidedly more neutral for rainfall, although temperatures are likely to remain above average for most of the country.
It is finally beginning to look like more tropical weather is returning to our north, with the chance of a cyclone developing early next week and tropical rainfall expected to move into inland Western Australia over the next few days.
ABC News reports for those in the south, while a return to neutral conditions is better than drier than average, average conditions over summer are still hot and dry.
Until there is widespread rainfall, fire and heatwave conditions will continue.
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