The 1978–79 Australian region cyclone season was the only season in which a reconnaissance aircraft flew into a tropical cyclone. Operationally, Australia's Bureau of Meteorology (BOM) tracked eleven tropical cyclones, while two additional systems were later added to the United States's Joint Typhoon Warning Center (JTWC) best track. Prior to 1985, the Australian region basin was defined as in the southern hemisphere between 80°E and 160°E, with the modern day season boundaries ranging from 1 November to 30 April of the following year. The first storm, an unnamed system, developed on 19 November 1978. The final cyclone, Kevin, dissipated by 12 May 1979. Tropical cyclones in this area were monitored by three Tropical Cyclone Warning Centres (TCWCs): the BOM in Perth, Darwin, and Brisbane.
Tropical cyclogenesis in the season began when an unnamed tropical cyclone developed well west of Australia on 19 November and lasted until 23 November after moving in a generally southward direction throughout much of its duration. Cyclone Peter developed over the Gulf of Carpentaria on 29 December. During and in the few days after landfall in Queensland on 31 December, the storm produced heavy precipitation in the state and became the rainiest tropical cyclone in Australia. Severe flooding occurred in the Cairns area, leaving two fatalities and about $10 million in damage. Gordon became the first system to enter from another basin, entering from the South Pacific on 9 January. The storm dissipated shortly after striking Queensland on 12 January, bringing rainfall and rough seas.
Cyclone Kerry remained in the Australian region from 12 February to 3 March, making it the longest-lived tropical cyclone in the basin on record. Hazel was the most intense tropical cyclone of the season, peaking as a Category 4 on the Australian tropical cyclone intensity scale. The storm brought rough seas and strong winds to Western Australia, resulting in $20 million in damage and 15 deaths after a fishing boat capsized. None of the subsequent tropical cyclones significantly effected land. Tropical cyclogenesis concluded with the formation of Kevin on 2 May, which dissipated on 12 May. Overall, the tropical cyclones of this season collectively caused 17 deaths and over $30 million in damage.
Season summary
Under the modern day boundaries, a season lasts from 1 November to 30 April of the following year, while a tropical cyclone year is defined as from 1 July to 30 June of the next year. Thirteen cyclones entered or formed in the Australian region, which was equal to the 1970–71 to 2001–02 average of 13 per season. By region, three cyclones developed over the Perth TCWC, three formed in the Darwin TCWC, and just one originated over the Brisbane area. Thus, seven cyclones developed in the Australian region – defined as the southern hemisphere between 80°E and 160°E – until Météo-France's Réunion area of responsibility and BOM adjusted the boundary eastward to 90°E in 1985. This was slightly below the 1952–53 to 1970–71 average of eight per season.
There was a total of eleven coastal crossings, which is either a landfall or a tropical cyclone moving from land to sea. This was well above the 1949–50 to 1974–75 average of five per season. This was the first and only season that reconnaissance aircraft flew into cyclones in this basin. A WP-3D Orion operated by the United States's National Oceanic and Atmospheric Administration (NOAA) flew into Cyclone Kerry on three occasions – 21 February, 22 February, and 4 March. Another flight mission was conducted for observing Cyclone Rosa as the storm was making landfall in Northern Territory on 26 February. Overall, the tropical cyclones of this season resulted in 17 deaths and slightly more than $30 million in damage.
Activity began in November 1978, when Tropical Cyclone 01S formed the Australian region in the Perth TCWC area on 18 November. The next cyclone, later designated as 03S, developed about a month later on 20 December. In addition, Peter formed on 29 December. January also featured two more cyclones, Greta and Gordon, the latter of which entered the basin from the South Pacific on 9 January. Likewise, there were two tropical cyclones in the month of February, Rosa and Kerry, both of which existed simultaneously for almost three weeks. Hazel and Ivan originated in March. The former was the most intense tropical cyclone of the season, peaking with 10-minute maximum sustained winds of and a minimum barometric pressure of . April was the most active, with three cyclones originating or entering the basin during that month. The last storm, Kevin existed in May between 2 May and 12 May, after the end of the modern day season, which is 30 April.