On December 8, 2002, the center of the eye of Typhoon Pongsona passed within approximately 10 km of Guam’s northeast coastline, with the southwestern semicircle of the eye wall cloud traversing most of the island. This typhoon was one of the most intense typhoons to strike Guam within the past 50 years. The maximum wind speed experienced on-island was determined to be equivalent to that of a Category 4 hurricane. This typhoon also produced 100-year return-period rainfall accumulations (at intervals from 15 minutes to 12 hours), and 100-year return-period peak stream flow values. The findings of an extensive post-analysis of the meteorological and hydrological data obtained during the passage of this devastating typhoon over the island of Guam are presented.