By early on October 17, the outer rainbands, which had previously controlled the structure of the cyclone, dissipated, while deep convection developed near and to the south of the center. Computer models predicted steady strengthening as the depression moved westward before turning to the north. Of the intensity models, the Geophysical Fluid Dynamics Laboratory predicted an intensity of 135 mph (215 km/h) within 36 hours, with other forecasts being more conservative in their predictions. Deep convection continued to develop to the south of the center, and the depression strengthened into Tropical Storm Wilma at 0600 UTC on October 17, while about 200 miles (320 km) southeast of Grand Cayman. Right after becoming a tropical storm, the National Hurricane Center predicted Wilma to track west-northwestward, reaching winds of 105 mph (170 km/h) before striking the northeastern portion of the Yucatán Peninsula. The storm continued to the southwest while deep convection laid near the center. National Hurricane Centner forecaster James Franklin said, "Confidence at the later ranges [of the forecast track] was unusually low", because of wide divergences between computer models. Late on October 17, a Hurricane Hunters flight into Wilma recorded winds of 50 mph (80 km/h), but an unusually low pressure of 989 mbar (29.21 inHg), which would be more typical of a minimal hurricane. This was because of a number of unusual low pressures across the region, which resulted in a lesser pressure gradient and thus lighter winds. Convection continued to develop near the center and became much more symmetrical.
Tropical Storm Wilma began to turn to the west-northwest on October 18, during which the storm developed a small, intermittent and ragged eye feature as well as a mid-level eye feature. It continued to strength, and at 1200 UTC on October 18, Wilma strengthened into a Category 1 hurricane while about 225 miles (360 km) south-southeast of Grand Cayman. Shortly after reaching hurricane strength, the hurricane began undergoing explosive deepening, subsequent to the development of a "pinhole" eye 9 miles (14 km) in diameter. This small eye was surrounded by a ring of deep convection, with cloud-top temperatures of about -125 °F (-87 °C).
Early on October 19, Wilma attained major hurricane status while continuing to rapidly intensify, and by 0600 UTC, the storm's maximum sustained winds increased to 170 mph (275 km/h), making Wilma a dangerous Category 5 hurricane on the Saffir-Simpson Hurricane Scale. In the span of just 24 hours, Wilma had intensified from a 70-mph (110-km/h) tropical storm to a 175-mph (280-km/h) Category 5 hurricane, an event that has never happened before for an Atlantic hurricane. The eye continued to contract to a diameter of about 3 miles (5 km), the smallest known eye in an Atlantic hurricane, and at 1200 UTC on October 19, Wilma reached peak winds of 185 mph (300 km/h). The central pressure quickly dropped 54 mbar (1.65 inHg) from 0000 to 0600 UTC.
At 0800 UTC, a Hurricane Hunters flight recorded a minimum central pressure of 884 mbar (26.10 inHg) in a dropsonde near the center of the extremely small eye. As the dropsonde did not reach the calm winds in the center, the pressure was estimated at 882 mbar (26.05 inHg), the lowest pressure in an Atlantic hurricane on record. The pressure continued to fall as the Hurricane Hunters left the hurricane, and it is possible the pressure was a little bit lower. Operationally, the peak intensity was estimated at 175 mph (280 km/h). At the time of its peak intensity, hurricane force winds extended only 50 miles (85 km) from the small center of Wilma, with tropical storm force winds extending only about 160 miles (260 km).
Shortly after peaking in intensity, the coldest cloud tops surrounding the eye warmed a little bit and an outer eyewall began to form, meaning that an eyewall replacement cycle was happening. By late on October 19, the winds in Hurricane Wilma decreased to 160 mph (260 km/h) as the inner 5 mile (8 km) wide eye weakened and the wind field expanded. Early on October 20 the hurricane weakened to Category 4 status after the small, inner eye dissipated and the 45 mile wide outer eyewall became the new eye. At the time, the pressure measured 892 mbar (26.34 inHg), the lowest known pressure for a Category 4 hurricane, and Wilma retained the large eyewall as it turned northwestward. Originally, the hurricane was forecasted to re-intensify into a Category 5 hurricane, with one forecast predicting it to make landfall on the Yucatán Peninsula with winds of 165 mph (265 km/h), though Wilma remained a strong Category 4 hurricane as it tracked northwestward.
Steering currents stayed weak, though a series of troughs eroded the high pressure system across the Gulf of Mexico, resulting in a turn towards the north-northwest. Environmental conditions remained favorable, with the eye becoming more distinct early on October 21. At about 2145 UTC on October 21, Wilma made landfall on the island of Cozumel with winds of 150 mph (240 km/h). It weakened a little bit as it continued northwestward, and struck the Mexican mainland near Puerto Morelos at 0330 UTC on October 22, with winds of 135 mph (215 km/h) and gusts of up to 170 mph (270 km/h).
On October 22, the mid-level ridge to the north of Wilma later dissipated, leaving the hurricane moving northward across the northeastern Yucatán Peninsula. As the hurricane moved farther inland, the eye became cloud-filled as the deepest convection began to warm, and the winds slowly weakened during its passage over land. About 26 hours after making landfall on Cozumel, Wilma emerged into the southern Gulf of Mexico near Cabo Catoche with winds of about 100 mph (160 km/h). After reaching open waters, Reconnaissance Aircraft reported the remains of an inner eyewall and an outer eyewall measuring between 70 and 90 miles (110 to 145 km) in diameter. Convection deepened around the eyewalls, and the inner core of convection, which had previously become disrupted over land, became a little bit more organized.
A powerful eastward-moving mid-level trough across the central United States turned the hurricane northeastward and caused it to gradually speed up. Vertical wind shear increased as strong upper-level southwesterly flow increased, though in spite of the shear Wilma continued to intensify. Early on October 24, Wilma re-gained major hurricane status while about 120 miles (195 km) west-southwest of Key West, Florida. It slowly became better organized, with the large 50 mile (80 km) eye becoming very distinct on satellite and radar imagery. Wilma was able to retain its strength because large eyes in tropical cyclones are more stable and more resistant to vertical wind shear. Despite wind shear values of about 30 mph (48 km/h), Wilma strengthened further to reach winds of 125 mph (200 km/h). It weakened a little bit as it approached Florida, and made landfall at Cape Romano with winds of 120 mph (195 km/h) at around 1030 UTC on October 24.