[1] The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) named the storm Gloria while the typhoon was in the vicinity of the country.

[3] The system rapidly organized that day, and at 2000 UTC the Joint Typhoon Warning Center (JTWC)[nb 2] issued a tropical cyclone formation alert.

[5] Early on June 28, the Japan Meteorological Agency (JMA)[nb 3] classified the system as a tropical depression near the Mortlock Islands in the Federated States of Micronesia;[6] around the same time, the JTWC also initiated storm advisories.

[6] After moving northwestward, the storm turned to the east, resuming a northwest track on June 30 due to a subtropical ridge to the north.

[5][6] By June 30, Chataan had steadily strengthened to severe tropical storm status, with 10-minute maximum sustained winds of 95 km/h (59 mph).

[3] The next day, Chataan briefly weakened to an intensity of 85 km/h (53 mph), although it began strengthening steadily on July 3,[6] when its center passed very near Weno in Chuuk State in the FSM.

At 1800 UTC that night, the JTWC upgraded Chataan to a typhoon,[3] and about 24 hours later the JMA followed suit while the storm was approaching Guam from the southeast.

At 0000 UTC on July 8, the typhoon reached its peak intensity of 175 km/h (109 mph) 10-minute sustained) while located near the Japanese island of Okinotorishima.

[6] The JTWC assessed that Chataan had reached its peak intensity of 240 km/h (150 mph) 1-minute sustained) about six hours earlier; on that basis, the agency classified the system as a super typhoon.

At around 1530 UTC on July 10, Chataan made landfall on the Bōsō Peninsula in Honshu with winds of about 100 km/h (62 mph) 10-minute sustained).

[6] While Chataan was in its formative stages and still tied to the monsoon trough, it produced a large area of heavy rainfall and strong winds that affected Pohnpei and Chuuk in the FSM.

In the day before Chataan affected the island, it dropped torrential rainfall due to its elongated structure and slow movement.

Persistent winds from the larger monsoon trough generated high surf and tides of 0.3 m (0.98 ft) above normal across the region.

[10] The rains causes severe flooding across the island that reached 1.5 m (4.9 ft) in some locations,[11] triggering at least 30 mudslides that killed 47 people.

[9][10] Chataan damaged roads and bridges, and high winds downed power lines,[11] which cut communications between islands.

[1] Although the center of the eye did not strike Guam, the eyewall affected the entire island with strong winds and heavy rainfall.

[9] The most significant effects were from the heavy rainfall, resulting in landslides in some areas and causing rivers to flow at above-normal rates; 14 stations reported either record flow rates or peak crests, including an island-wide peak crest of 8.55 m (28.1 ft) at the mouth of the Tolaeyuus River.

In Apra Harbor, high seas washed ashore or sank five boats, and a Navy barge spilled 397,000 litres (105,000 gallons) of oil.

[23] At least 396 schools were closed in the country,[22] and a baseball game between the Yokohama DeNA BayStars and the Yakult Swallows was canceled due to the inclement weather.

[8] Six people who were seriously injured on Chuuk were flown to The Queen's Medical Center in Hawaii for treatment; they were initially scheduled to fly to Guam Memorial Hospital, but the facility was full.

[12] On July 3 while Chataan was passing the region, the governor of Chuuk declared a state of emergency,[10] requesting international assistance.

Because the FSM is in a Compact of Free Association and not a U.S. state, the Federal Emergency Management Agency (FEMA) could not provide immediate assistance.

[39] On July 30, FEMA announced that residents and business owners in Chuuk could apply for individual assistance, including money for housing, repairing damage, and low-interest loans.

[40] The declaration would not apply to outer islands in Chuuk, which did not sustain significant damage; this is because FEMA only had funds to restore areas to how they were before the storm.

[41] Ultimately, FEMA provided 93,000 L (25,000 US gal) of water, 1,300 blankets, 45,360 km (100,000 lbs) of rice, 11,328 meals ready to eat, and various other supplies.

[42] In total, the agency allocated $10.6 million, mostly in the form of individual assistance that provided money for purchasing lost supplies.

[43] FEMA ultimately sent just under $5 million to Chuuk after Chataan, as well as subsequent typhoons Pongsona and Lupit; however, about $445,000 of the funding was believed to have been misspent due to discrepancies discovered in an audit in 2006.

[9] Before the facility reopened, the Guam Waterworks Authority distributed water to the island at differing times of the day to ration the limited supply.

[14] On August 7, President George W. Bush also declared Rota to be a disaster area, which provided funding for debris removal.

Countries in the World Meteorological Organization can request tropical cyclone names to be retired if a storm caused unusually heavy damage.