[1] On 5 November, the JTWC started to monitor a tropical disturbance, that was located about 840 km (520 mi) to the southeast of Jakarta, Indonesia.

However, when the system was added to their database, it was estimated that while it was in the Australian region it had peaked as a Category 2 tropical cyclone with 10-minute windspeeds of 95 km/h (60 mph).

[3] Over the next few days the system moved eastwards and slowly intensified further before TCWC Brisbane named it Delilah, during 1 January after it had developed into a category 1 tropical cyclone on the Australian scale.

By 23 January, a low-pressure area developed to the northwest of Christmas Island and the system was classified a tropical low.

Two days later, the system passed just 20 km (12 mi) north of the Cocos Islands, where wind gusts reached 70 km/h (43 mph) and pressures dropped to 999 mb (hPa; 29.50 inHg).

Weakening below cyclone strength that day, John continued over the open waters of the southeast Indian Ocean before completely losing its identity on 2 February well to the west of Australia.

Steady strengthening ensued as the newly named Leon approached the western bounds of the Australian cyclone region.

Cyclone Leon–Hanitra ultimately attained peak winds of 150 km/h (95 mph) and a pressure of 940 mb (hPa; 27.76 inHg) before turning south and becoming extratropical.

Harry gradually strengthened over the following two days, ultimately attaining its peak intensity on 15 February with winds of 205 km/h (125 mph) and a minimum pressure of 925 mbar (hPa; 27.32 inHg).

[8] On 23 February the BoM started to monitor a tropical low that had developed within the monsoon trough about 1,665 km (1,035 mi) to the north of Perth, Western Australia.

[9][10] Over the next day the system moved southwards before it was designated as Tropical Cyclone 16S by the JTWC, as it reached its peak intensity with 1-minute sustained wind speeds of 85 km/h (55 mph).

[10][11] The system subsequently made landfall on Western Australia during 24 February, having nearly become a tropical cyclone on the Australian scale.

[13] High winds in Collie caused a starting pontoon along the Wellington Dam course in the Australian Rowing Championships to sink.

[15] The entire King's Cup portion of the championships was abandoned, marking the first time since World War II that it was cancelled.

[20] Despite Orson's extreme intensity, damage was relatively minimal as it struck a sparsely populated region of Western Australia.