[2] Over the next day the system gradually developed further underneath an upper level ridge of high pressure, within an area of moderate vertical wind shear, as it slowly moved towards the southwest.

[2][3] RSMC Nadi subsequently classified the disturbance as a tropical depression early on January 4, as the systems low level circulation centre consolidated.

[8] During that day the systems organization significantly improved with RSMC Nadi reporting at 18:00 UTC that Ian had become a category three severe tropical cyclone.

[9] Over the next day the system developed a cloud filled eye and intensified into a category 4 severe tropical cyclone.

[10] Late on January 10, a state of emergency was declared by Tongan Prime Minister Lord Tu'ivakano, after Ian intensified into a category five severe tropical cyclone[11] with 287 km/h winds.

[19] Australia provided A$50,000 in emergency supplies including blankets, water containers, tarpaulins, kitchen sets and hygiene kits.

[15] In accordance with the FRANZ agreement, enacted in 1992, the Government of France established an air route from Nuku'alofa to Ha'apai and deployed an aircraft carrier from New Caledonia.

[22] The Japanese Government provided 600 jerrycans and 30 water tanks (3,700 litre capacity), collectively worth ¥13 million ($127,000 USD).