[2] Megi killed 31 people and caused $255.1 million (2010 USD) in damage over Luzon, making it top twenty of the costliest typhoons in the Philippines.

[7] The system began to significantly develop on October 12, prompting the Joint Typhoon Warning Center (JTWC) issuing a Tropical Cyclone Formation Alert at 09:00 UTC.

[16][17] On October 16, Megi began rapid deepening with a well-defined eye due to enhanced poleward outflow by a transitory mid-latitude trough.

[21] A hurricane hunter aircraft indicated 1-minute maximum sustained surface winds at 165 knots (305 km/h; 190 mph) and a mean sea level pressure of 890 hPa (26.28 inHg) at 13:05 UTC.

Late on October 17, Megi developed a well-defined 25 nautical miles (46 km; 29 mi) diameter eye with a concentric eyewall and excellent radial outflow.

[1][24] When passing the Sierra Madre, the eye filled due to land interaction, but tightly curved banding and excellent radial outflow remained.

[28] Typhoon Megi turned northward then north-northeastward towards a break in the subtropical ridge caused by an approaching mid-latitude trough on October 20.

[30] On October 21, JMA reported that Megi attained its secondary peak intensity by the 10-minute maximum sustained winds reaching 95 knots (175 km/h; 110 mph) and the atmospheric pressure decreasing to 935 hPa (27.61 inHg), when the typhoon had a 40 nautical miles (74 km; 46 mi) diameter round eye.

[31] On October 22, the eye of Typhoon Megi became cloud-filled and convection begun eroding due to increasing vertical wind shear.

[2][34] Soon, Megi weakened to a tropical storm in mainland China, as the majority of convection associated with the system has dissipated, prompting JTWC issuing a final warning.

[42] Late on October 16, PAGASA issued Storm Signal 1 for Cagayan, Isabela, Babuyan and Calayan islands in the northern Philippines,[43] while President Aquino called for cooperation from all concerned government and private sector groups to prevent fatalities.

[44] On October 17, evacuations began with hundreds of people fleeing from Luzon[45][46] as Megi intensified into a super typhoon and Storm signal number 3 raised.

[55] China began preparing for Super Typhoon Megi on October 17 by issuing an orange alert to local authorities and advising all vessels to return to port.

[56] Evacuation of coastal residents began on October 18[57] as authorities issued disaster warnings and urgent advice to local officials in Hainan, Guangxi, Guangdong and Fujian provinces to prepare for relief operations.

[58] The government ordered all fishing vessels to return to port by midnight on October 19 as Typhoon Megi entered the South China Sea.

[61] As the typhoon approached, over 150,000 residents from coastal areas of Fujian province were evacuated and tens of thousands of fishing vessels were ordered to seek shelter in port.

The centre of the storm made landfall near Divalacan Bay, Luzon, at 11:25 am (local time) on October 18 preceded by torrential rain and flash flooding[66][67] forcing residents of the area to seek shelter.

[68] A reported total of 3,687 individuals from the northern Philippines[69] were evacuated to schools, churches, halls and other sturdier structures[70] but over 200,000 people were rendered homeless.

The National Grid Corp. announced that eleven towers along one transmission line suffered extensive damage, which also affected power supplies to the capital leading to outages of up to 3 hours.

[89] Many roads in Luzon remained closed through October 18,[90] and bus operators cancelled trips to Cagayan and Isabela due to the poor weather.

[105][106][107] The president made a statement expressing his sympathy and condolences for the bereft families, while also declaring that despite the strength of Megi, the loss of life was significantly less than during Typhoon Basyang and Tropical Storm Ondoy.

[115][116] Throughout Yilan County, torrential rainfall from Typhoon Megi and the northeast monsoon, peaking at 1,182 mm (46.5 in) in Suao,[117] triggered widespread flash flooding and landslides.

Torrential rainfall caused a 500 m (1,600 ft) section of a nearby mountain to collapse, burying a bus carrying 19 people, whom officials fear may have all perished.

A total of 36,050 hectares of crops and 530 houses were destroyed by the storm with overall losses incurred in Fujian Province reaching 2.8 billion yuan (US$411.7 million).

[5] The Japan Meteorological Agency (JMA) analysed that the 10-minute maximum sustained winds of Typhoon Megi in 2010 was 125 knots (232 km/h; 144 mph), making it the second strongest tropical cyclone in the Northwest Pacific Ocean on record along with Bess in 1982 and Haiyan in 2013, only after Tip in 1979.

[125] The Hong Kong Observatory analysed that Megi was the strongest tropical cyclone in the Northwest Pacific Ocean since Tip in 1979 by attaining the 10-minute maximum sustained winds at 270 km/h (145 knots, 165 mph).

[126] A hurricane hunter aircraft indicated 1-minute maximum sustained surface winds of 165 knots (306 km/h; 190 mph) and minimum pressure was 890 hPa (26.3 inHg) at peak intensity, which was equivalent to Tip in 1979.