The South Pacific convergence zone was active in the middle of December 1986, with a mid-latitude upper-level trough of low pressure which extended into the tropics. A westerly wind burst between Tokelau and Kanton Island resulted in a tropical disturbance developing northeast of Tokelau. The Fiji Meteorological Service (FMS) began to monitor the disturbance as a shallow tropical depression on 21 December, when the system was about 280 km (175 mi) east of the island of Funafuti, Tuvalu.[nb 1] At that time, the system was beyond the range of any reporting stations; its circulation was weak and ill-defined, which meant that there was considerable uncertainty about the location of its center. The depression moved southwest and passed near the Tuvaluan atoll of Nukufetau, as it slowly deepened and organised over the next 36 hours.
The system was named Tropical Cyclone Raja by the FMS on 23 December; the United States Naval Western Oceanography Center (NWOC) began issuing advisories, designating it as Tropical Cyclone 04P.[nb 2] During that day, the system slowed as it approached Rotuma; the subtropical ridge of high pressure weakened, and widespread falling pressure was recorded across the Pacific. Raja then unexpectedly re-curved southeast and began moving towards the French territory of Wallis and Futuna on 24 December. Satellite imagery the next day indicated that the system had developed an eye, and it passed within 55 km (35 mi) of Futuna. Raja reached hurricane strength on 26 December, as it slowed and began to interact with what would become Severe Tropical Cyclone Sally. Over the next two days, Raja approached to within 1,110 km (690 mi) of Sally in an anticlockwise cyclonic loop as it continued to intensify. The system also passed about 110 km (70 mi) southeast of Futuna, as it re-curved east and began to threaten Fiji.
The FMS estimated on 28 December that Raja had peaked with 10-minute sustained wind speeds of 150 km/h (90 mph), which made it a Category 3 severe tropical cyclone on the Australian tropical cyclone intensity scale. The system turned southwest that day, in response to a trough of low pressure developing over (and south of) Raja and Sally. It passed within 20 km (10 mi) of Cikobia and Udu Point on Vanua Levu on 29 December, before it passed over or near several smaller Fijian islands in the Lau Group while beginning to turn south. The NWOC estimated that Raja had peaked in intensity at this time with one-minute sustained wind speeds of 165 km/h (105 mph), equivalent to a Category 2 hurricane on the Saffir-Simpson hurricane wind scale. Over the next few days, Raja gradually weakened as it moved over cooler waters south of Fiji and its outflow became restricted before it degenerated into a depression during 1 January. The depression passed under a subtropical jet and moved west, where it became part of a blocking pattern over New Zealand. The system was last noted on 5 January, after filling over the north Tasman Sea.