During February 23, the Fiji Meteorological Service reported that Tropical Disturbance 10F, had developed within the monsoon trough about 700 kilometres (435 mi) to the west of the Tuvaluan atoll of Funafuti.
The system was then located just south of a 250-hPa ridge axis, in a diffluent region.
Wind shear and diurnal variations were evidently influencing development.
Sea surface temperatures (SST) were around 31 °C.

Later on February 24, shear had decreased markedly.
Outflow was favorable and developing in all quadrants.
Overnight, the tropical depression underwent explosive development, with the deep convection increasing spatially and in organization while cooling.
Spiral bands were also wrapping tightly around the low-level circulation center (LLCC).
Since the depression was located in an area of low wind shear and warm water temperatures, the storm was able to quickly strengthen into Tropical Storm Percy, by 1800 UTC on February 24.
At this point in time, Percy was located 120 miles (190 km) east of Fongafale, Tuvalu, and was moving towards the east-southeast at 14 kt (16 mph, 26 km/h).

On February 26, Percy reached Category 1 status, while located 400 miles (644 km) north of American Samoa.
While Percy moved east-southeast, a shortwave trough developed southwest of the storm.
The trough caused the cyclone to intensify even further to a Category 3 storm, as it passed between Fakaofa and Swains Island.
Percy then reached its initial peak at Category 4 status north of Pago Pago, as its winds reached over 135 mph (115 knots, 213 km/h) and the barometric pressure at its center fell to 925 millibars.
On February 27, Cyclone Percy encountered a ridge of high pressure, which slowed its forward speed.
Because of this, the cyclone's structure became elliptical, which caused the cyclone to weaken back to Category 3 status.
By February 28, Percy bypassed the Pukapuka and Nassau Islands as a Category 3 tropical cyclone, as it continued to move south-southeastward.

By then, the cyclone was re-organizing as the storm was steered to the southeast.
On March 2, Percy reached its peak intensity, with sustained winds reached 160 mph (140 knots, 265 km/h) on the Saffir-Simpson Hurricane Scale, and an estimated barometric pressure of 900 millibars.
Cyclone Percy maintained Category 5 status for 18 hours, while located 110 mi (177 km) west of Palmerston Island.
After reaching Category 5 status, Percy began to weaken, due to increasing wind shear.
During its weakening phase, Cyclone Percy passed south of Tropical Depression 20S. Pulled by an upper level trough, Percy swung to the east, passing Tropical Depression 24S in the process, before being caught up by another trough.
By March 4, the center of Percy became detached from the main area of convection and Percy quickly weakened to a tropical storm.
Tropical Storm Percy then quickly accelerated to 20 kt (23 mph, 37 km/h) as it became an extratropical storm.
Percy briefly entered the New Zealand area of responsibility before becoming extratropical at 1200 UTC.
By March 5, the remnants of Percy finally dissipated 700 miles (1127 km) southwest of Rarotonga.
During February 23, the Fiji Meteorological Service reported that Tropical Disturbance 10F, had developed within the monsoon trough about 700 kilometres (435 mi) to the west of the Tuvaluan atoll of Funafuti. The system was then located just south of a 250-hPa ridge axis, in a diffluent region. Wind shear and diurnal variations were evidently influencing development. Sea surface temperatures (SST) were around 31 °C.
Later on February 24, shear had decreased markedly. Outflow was favorable and developing in all quadrants. Overnight, the tropical depression underwent explosive development, with the deep convection increasing spatially and in organization while cooling. Spiral bands were also wrapping tightly around the low-level circulation center (LLCC). Since the depression was located in an area of low wind shear and warm water temperatures, the storm was able to quickly strengthen into Tropical Storm Percy, by 1800 UTC on February 24. At this point in time, Percy was located 120 miles (190 km) east of Fongafale, Tuvalu, and was moving towards the east-southeast at 14 kt (16 mph, 26 km/h).
On February 26, Percy reached Category 1 status, while located 400 miles (644 km) north of American Samoa. While Percy moved east-southeast, a shortwave trough developed southwest of the storm. The trough caused the cyclone to intensify even further to a Category 3 storm, as it passed between Fakaofa and Swains Island. Percy then reached its initial peak at Category 4 status north of Pago Pago, as its winds reached over 135 mph (115 knots, 213 km/h) and the barometric pressure at its center fell to 925 millibars. On February 27, Cyclone Percy encountered a ridge of high pressure, which slowed its forward speed. Because of this, the cyclone's structure became elliptical, which caused the cyclone to weaken back to Category 3 status. By February 28, Percy bypassed the Pukapuka and Nassau Islands as a Category 3 tropical cyclone, as it continued to move south-southeastward.
By then, the cyclone was re-organizing as the storm was steered to the southeast. On March 2, Percy reached its peak intensity, with sustained winds reached 160 mph (140 knots, 265 km/h) on the Saffir-Simpson Hurricane Scale, and an estimated barometric pressure of 900 millibars. Cyclone Percy maintained Category 5 status for 18 hours, while located 110 mi (177 km) west of Palmerston Island. After reaching Category 5 status, Percy began to weaken, due to increasing wind shear. During its weakening phase, Cyclone Percy passed south of Tropical Depression 20S. Pulled by an upper level trough, Percy swung to the east, passing Tropical Depression 24S in the process, before being caught up by another trough. By March 4, the center of Percy became detached from the main area of convection and Percy quickly weakened to a tropical storm. Tropical Storm Percy then quickly accelerated to 20 kt (23 mph, 37 km/h) as it became an extratropical storm. Percy briefly entered the New Zealand area of responsibility before becoming extratropical at 1200 UTC. By March 5, the remnants of Percy finally dissipated 700 miles (1127 km) southwest of Rarotonga.
Cyclone Percy