On 12 February a cloud cluster was located south of Christmas Island and circulatory features could be identified on the satellite imagery near the eastern edge of this cluster. The system moved eastwards, deepened slowly, and attained cyclonic strength at 1800 UTC on the 14th. Harriet reached peak intensity at 0600 UTC on the 15th with an estimated pressure of 988 hPa and estimated winds near the centre of 90 km/h.
Harriet failed to develop into a severe cyclone, possibly as a result of the upper tropospheric easterly flow which caused a shearing process that prevented the low level centre moving under the deep convective cloud mass.
Late on the 16th the centre recurved to the west as it came under the influence of a ridge of high pressure centred south of the storm. On the 18th Harriet displayed an erratic path but drifted west northwest during its decaying stages on the 19th and 20th.