The first named storm of the 2006 Pacific typhoon season, Chanchu formed on May 8 in the vicinity of the Federated States of Micronesia and progressed westward.

Warm waters and favorable outflow allowed the storm to quickly intensify to peak maximum sustained winds of 175 km/h (109 mph) on May 15.

Despite a general warning against small boats sailing, a ferry departed Masbate and capsized due to the storm, killing 28 people.

[nb 1] While in the South China Sea, Chanchu caught many Vietnamese fisherman off guard, causing 17 ships to sink and damaging several others.

Chinese ships assisted in the search-and-rescue mission, ultimately rescuing 330 fishermen from 22 boats; however, 21 bodies were found, and the remaining 220 missing were presumed killed.

In southern China, flooding and strong winds from Chanchu wrecked about 14,000 houses and damaged over 190,000 ha (470,000 acres) of crop fields.

[1] At 06:00 UTC on May 8, the Japan Meteorological Agency (JMA)[nb 2] declared that a tropical depression had developed about 175 km (109 mi) northeast of Palau.

Despite moving through the archipelago, Chanchu intensified slightly within the Sibuyan Sea, striking Mindoro on May 12 with 1 minute winds of 160 km/h (99 mph), according to the JTWC.

[5] According to the Hong Kong Observatory, the 10 minute winds reached 185 km/h (115 mph),[5] which made Chanchu the strongest typhoon in the South China Sea in the month of May.

[5] Early on May 18, the JTWC discontinued advisories, although the JMA continued tracking Chanchu over southeastern China through eastern Fujian province.

[16] Vietnamese fishermen in the South China Sea received 24 hours of warning from the National Hydrometerological Forecast Center before Chanchu approached the area, less time than other agencies in the region.

In response to the threat, officials at the Hong Kong Observatory, as well as in Macau, issued a standby signal to inform the public of the approaching typhoon.

[19] Ahead of the storm, about 1 million people evacuated from coastal Guangdong and Fujian provinces to government warehouses, schools, tents, or the houses of relatives.

Rough seas sank a ferry off Masbate, despite a warning against the operation of small craft, having left at sunrise to avoid the police.

[29] The typhoon brought the onset of the summer monsoon in the South China Sea after shifting the prevailing winds over the region.

[30] While moving slowly through the South China Sea, Chanchu produced strong waves that struck the east coast of Vietnam.

The associated flooding washed away many shrimp from coastal ponds and also entered Thu Bồn River, thus preventing its use as a source for irrigation for about 1,000 ha (2,500 acres) of rice paddy fields.

Rainfall in the country spread across Guangdong, Fujian, Jiangxi, and Zhejiang,[35] and Chanchu became the earliest typhoon to affect Shanghai in 80 years.

[21] While passing east of Hong Kong, the outer rainbands of Chanchu dropped 43.5 mm (1.71 in) of rainfall at Sha Tin.

Chanchu produced a storm surge of 0.77 m (2.5 ft), causing minor flooding, sinking a yacht, and injuring one person who was swept into the sea.

[8] High waves in Taiwan washed an oil tanker ashore in Kaohsiung City; all 13 crew members were rescued with helicopters.

[40] The remnants of Chanchu produced 121 mm (4.8 in) of rainfall in Gifu Prefecture in combination with a nearby cold front, causing one landslide.

[25] The trough that engulfed Chanchu drew moisture from the typhoon, leading to heavy rainfall in portions of South Korea that reached 144 mm (5.7 in) on Jeju Island.

[42] In the days after Chanchu moved through the Philippines, then-President Gloria Macapagal Arroyo ordered that the country's National Disaster Coordinating Council help all towns affected by the storm.

[46] Immediate after Chanchu's China landfall, officials began distributing tents, quilts, water purification tablets, and disinfectant.

[48] The Chinese government recognized 50 people who assisted in the South China Sea search and rescue mission, and two vessels were declared "hero ships".

[50] Residents and industries in Vietnam raised ₫360 million (VND, US$36,000)[nb 6] for the families of the deceased fishermen, as well as providing 1 ton of rice.

[55] The country's Ministry of Labour, Invalids and Social Affairs presented an award to the Vietnam News Agency in June 2006 for its charitable donations, which included the distribution of ₫112 million (VND, US$11,200)[nb 6] to storm victims.

[57] The head of the Vietnam Institute of Meteorology, Hydrology and Environment resigned two weeks after Chanchu killed many fishermen because of inadequate warnings.

[59] After the season ended, members of the 39th meeting of the Typhoon Committee of the World Meteorological Organization met in Manila in December 2006.