IN A year summed up by the recently-released Bureau of Meteorology’s annual climate statement as dry and hot for most of Australia, SA set records for low rainfall and high temperatures in 2018.
BoM senior climatologist Darren Ray said April stood out as particularly warm – the warmest for SA as a whole in more than 100 years of records.
More than 16 regions across SA recorded new highest daily maximum temperatures during April, while the state as a whole had a mean temperature 3.42 degrees Celsius warmer than average.
The hottest day of the year fell on December 28, at Tarcoola, in the state’s Far North, which reached 48.1C.
Mr Ray highlighted September as particularly dry – even in a year of reduced rainfall totals.
BoM records show it was the driest September on record nationally and the second driest for SA.
But Mr Ray said it was also the driest September for all of SA’s agricultural region.
He said that month also had a strong high pressure system, which was conducive for frost, as seen in a number of areas, particularly the Mid North.
BoM records show the state’s rainfall was 24 per cent below the average for the entire 2018.
Roxby Downs recorded only 36pc of its annual rainfall with 51.2 millimetres for 2018, compared with an average 143.2mm.
Port Augusta received 52pc of its average rainfall, Kadina 54pc and Renmark 63pc.
Port Germein was one of five towns to record its lowest annual rainfall – 170.5mm for the year, against an average 325.8mm. This was its lowest in 136 years.
But while large areas of the state received below average rainfall, this was not the case everywhere, according to Mr Ray, with the South East and West Coast, as well as North West Pastoral areas receiving average to above-average rain in parts.
“It was a mixed story – the (lower) SE overall did fairly well (for rainfall) and Ceduna was a wetter year as well,” he said.
“We’re seeing a trend that areas along the coast pick up regular rainfall – that certainly was the case last year.”
Ceduna received 97pc of its annual average, the Nullabor 122pc, Mount Gambier 108pc and Cape Borda, on Kangaroo Island, recorded 99pc of its average fall.
Nationally, Bureau senior climatologist Lynnette Bettio said the Indian and Pacific ocean climate drivers were largely neutral in 2018, which allowed local influences to act.
In SA, Mr Ray said 2018 started with a very weak La Nina in effect in the Indian Ocean, but this did not have the typical La Nina impacts and faded quickly.
In May, the climate entered a weak positive phase in the Indian Ocean Dipole, he said, which would generally tend to result in cooler weather.
“There was less moisture feeding down the country, and less rainfall,” he said.
He said there was also a strong ozone hole, which impacts on weather systems.
“This could have contributed to wetter end of the year,” he said.
While the Bureau had been monitoring the possibility of an El Nino event during spring, this did not form, similar to 2014, Mr Ray said.
“What this means is there is some risk of an El Nino event this year, like that seen in 2015,” he said.
“There is the risk of another hot, dry year if El Nino develops, on top of two hot and dry years.”
He said this would typically form from June to August but could start as early as May, as in 2015.