Under favorable conditions, the disturbance gradually organized, becoming a depression two days later, before strengthening to a tropical cyclone, earning the name Sarai.

Sarai passed near the Tongan islands of Haʻapai and Tongatapu as a Category 1 cyclone, before rapidly degrading to a tropical depression due to the system entering unfavorable conditions.

During December 20, the Fiji Meteorological Service (FMS) started to monitor an area of low pressure, located near the Solomon Islands for the possibility of tropical cyclogenesis.

During December 23, the FMS reported that the area of low pressure had developed into a tropical disturbance and assigned it the designator 03F, while it was located about 630 km (390 mi) to the west of Tuvalu.

[4][5] At this time the system was poorly organised with deep atmospheric convection, displaced to the north and east of its broad and elongated low-level circulation.

[4][6] The disturbance was also located underneath an upper ridge of high pressure within a favourable environment for further development, with low to moderate vertical windshear and warm sea surface temperatures of 29–30 °C (84–86 °F).

[5] However, it was noted that the movement of tropical cyclones could be erratic within the region and that some weather models were predicting that the system would make landfall on Viti Levu.

[5][7] Over the next couple of days, the system moved southwards and gradually developed further with its overall organisation improving, before it was classified as a tropical depression by the FMS during December 25.

[11][13] Over the next couple of days, the system gradually intensified further and was classified as a Category 2 tropical cyclone during December 27, while it was located around 220 km (135 mi) to the west of Nadi, Fiji.

[16][17] During December 28, as Sarai passed about 100 km (60 mi) to the south of Fiji's Kadavu Island, the FMS estimated that the system had peaked as a Category 2 tropical cyclone with 10-minute sustained winds of 110 km/h (70 mph).

[19] Over the next couple of days, the system gradually weakened as it was steered eastwards towards Tonga, with its low level circulation center becoming partially exposed and atmospheric convection significantly decreased as vertical wind shear increased.

[20][21] During December 30, the FMS reported that Sarai had weakened into a Category 1 tropical cyclone, before it passed over the Tongan island groups of Ha'apai and Tongatapu later that day.

[25][26][27] The remnant tropical depression continued to move east-southeastwards and passed about 215 km (135 mi) to the southeast of the island nation of Niue later that day.

[33][37] Flash flood warnings issued by the FMS prompted the evacuation of 360 people to 15 shelters in the city of Lautoka and on the island of Ovalau.

[48] This warning was cancelled by the FMS later that day as Sarai weakened into a tropical depression, however, it was still expected to produce strong winds of up to 55 km/h (35 mph) on the island.

[49] As a result of these conditions, the Cook Islands Police Service warned residents to exercise extreme caution and avoid beachfront areas on the western side of Rarotonga, including the seawall in Nikao.

[28] Various people ignored the warnings imposed in the southern Cook Islands and lined the beaches to take photos of the storm while others drove their vehicles and bikes through the high waves that had come in over the seawall and covered the road.

[50] Boats docked within Avatiu Harbour were severely impacted, while the police vessel Te Kukupa smashed its mooring and had to be taken to the northern side of the island to wait out the storm.