The 1973 Pacific typhoon season was the latest start to the typhoon season on record. It had no official bounds, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean.
Tropical Storm Bille, which developed on July 12 east of the Philippines, rapidly strengthened on the 14th and 15th to a 150 mph super typhoon. It tracked due north, fluctuating in intensity for the next 3 days. A building ridge over the Sea of Japan forced Billie to the northwest, where it weakened greatly, first to a tropical storm on the 18th, then to a tropical depression on the 19th as it passes over northeastern China. The storm dissipated on the 20th.
The monsoon trough spawned a tropical depression east of the Philippines on October 1. Under weak steering currents, it meandered westward, where favorable conditions allowed for it to strengthen, first to a tropical storm on the 2nd, then to a typhoon on the 3rd. Nora continued to the northwest, and explosively deepened on the 5th and 6th to a 185 mph super typhoon. At the time, it had a minimum central pressure of 877 millibars, the lowest pressure on record at the time and currently tied for 9th. The typhoon weakened as it headed to the northwest, and struck northeastern Luzon on the 7th as a 115 mph typhoon. Nora continued to the northwest, weakening to a minimal typhoon as it hit southeast China on the 10th. The typhoon caused 18 fatalities, with over $2 million in damage.
27 people were killed when Typhoon Ruth crossed Luzon on October 15 and caused $5 million in damage. Ruth continued to the northwest, and hit Hainan Island and China on the 19th and 20th, respectively.
The Philippine Atmospheric, Geophysical and Astronomical Services Administration uses its own naming scheme for tropical cyclones in their area of responsibility. PAGASA assigns names to tropical depressions that form within their area of responsibility and any tropical cyclone that might move into their area of responsibility. Should the list of names for a given year prove to be insufficient, names are taken from an auxiliary list, the first 10 of which are published each year before the season starts. This is the same list used for the 1969 season. PAGASA uses its own naming scheme that starts in the Filipino alphabet, with names of Filipino female names ending with "ng" (A, B, K, D, etc.).