The 48-year-old will become head cricket coach at the Northern Institute of Sport in Darwin.
"It is a fantastic opportunity but one which I am only accepting because my whole family are able to join me in Australia. That was the clinching factor," Judd said. "I obviously have mixed feelings about leaving Scotland because I have many brilliant memories both with Greenock and the Saltires."
Judd, who arrived in Scotland from Tasmania a decade ago, enjoyed unprecedented success first as coach of Greenock and then in charge of the national side. He led the Scots to their first international title when they won the ICC Intercontinental Cup in 2004. However, his crowning achievement came a year earlier when the Saltires entered the Totesport League and beat three counties in the space of 20 days.
Judd turned down the opportunity to become full-time national coach in 2005, opting to honour his contract with Greenock, but was brought back into the fold as No 2 and video analyst by current coach Pete Steindl in 2009.
Meanwhile, Northants wicketkeeper David Murphy is line to make his Scotland debut today. Murphy, one of four English-born players selected for the tour to South Africa, missed the first week due to prior commitments, but he arrived in Potchefstroom on Friday and is likely to take part in today's 50-over clash with North West Dragons.
Steindl must decide whether Murphy or Richard Coughtrie will take the gloves with the other man likely to play as a specialist batsman.