On 21 December a tropical Low had developed within the monsoon trough to the southeast of Sumatra, Indonesia. Over the next few days the system gradually developed further as it moved
south-eastwards, before it started to move towards the south-west and the Cocos (Keeling) Islands during 23 December. Early the next day, it intensified into a Category 1 tropical
cyclone, and named Kate. The next day, Kate continued to intensified as an eye developed and reached peak intensity as a Category 4 severe tropical cyclone. On 27 December, it underwent
an eyewall replacement cycle. On 30 December Kate had moved out of the Australian region and into the South-west Indian Ocean basin.