The 1940 Pacific typhoon season marked an interruption in meteorological records in both the Philippines and Hong Kong due to the start of World War II. There were 43 reported tropical cyclones, including 27 that attained typhoon status. The first storm was observed in February, and the first typhoon formed two months later, killing three people along Mindanao. Several storms formed in June and July, including reports of a typhoon in the newspapers that killed 52 in South Korea, and another typhoon reported in newspapers that killed one person on Samar after dropping heavy rainfall. The strongest typhoon of the season originated in July and attained a minimum pressure of , as reported by a ship northeast of the Philippines.
On August 18, a typhoon moved near or over northeastern Luzon, killing nine people. In early September, a typhoon passed through the Bonin Islands south of Japan and later moved near Kyushu; heavy rainfall caused a reservoir to collapse in Ōita Prefecture, killing 50 people. On September 18, a typhoon caused a tram collision in Tokyo due to poor visibility, killing 20. Another typhoon struck southern Taiwan on September 29, causing 50 fatalities. On October 19, Wake Island recorded typhoon-force winds for the first time since observations began five years prior. A strong typhoon passed near Guam on November 3 with winds of 200 km/h (125 mph), damaging most of the buildings on the island and killing five. Three storms affected the Philippines in December, the second of which was the most notable; it killed 63 people and left 75,000 homeless on Catanduanes. The third of the Philippine storms dissipated on December 24, ending activity for the season. There was another December typhoon that killed two people on a ship to the northeast of Guam.
Systems Data for most of the storms were provided through the World Wide Consolidated Tropical Cyclone data file known as TD-9636. The document utilized several sources to indicate where storms were located, and as a result there were duplications. During the season, the Philippine Weather Bureau issued monthly bulletins, which later provided info for tropical cyclone tracks. The agency used weather stations that were established by Spain and the United States after each country ruled over the archipelago. The weather data ceased in August 1940, which were later rebuilt in 1945. Also in 1940, meteorology records were disrupted in Hong Kong, which were later restored in 1947, due to World War II.
February and April On February 1, a tropical cyclone formed over western Mindanao in the Philippines. It moved northwestward across Palawan island and was last noted later on February 1. Historical weather maps show only a circulation near 9 N 121 E. This was a weak system, likely a depression but may have been a weak Tropical Storm.
Two months later, a tropical depression developed on April 9 to the east of Yap in the western Caroline Islands. It moved west-northwestward, passing south of the island without gaining much intensity. The depression later bypassed Palau to the north, dissipating on April 13 about 400 km (250 mi) west-northwest of the island.
On April 23, a tropical cyclone was observed east of Palau, moving to the west-southwest. It curved south of the island before turning to the west-northwest. While the storm was approaching Mindanao, a ship reported a minimum pressure of 985 mbar (29.09 inHg) and force 12 on the Beaufort scale, indicating that the system was a typhoon. Early on April 26, the typhoon made landfall just south of Port Lamon on eastern Mindanao, where a pressure of was reported. Along the coast, the storm produced strong winds and heavy rainfall, and killed three people after capsizing a boat. The storm later crossed over Negros island and near Cebu, where winds of were reported. The storm later entered the South China Sea, dissipating near Palawan on April 28.
June and July
A preexisting low pressure area organized into a tropical cyclone on June 9 near Chuuk State. It moved to the northwest as a tropical depression, influencing the trade winds on Yap. On June 13, the storm executed a small loop to the southwest, later turning back to the northwest. It eventually intensified into a typhoon, producing a pressure of in the Ryukyu Islands while passing to the east. The system was no a longer a tropical cyclone by June 16, either due to dissipation or becoming an extratropical cyclone that continued to the northeast toward Alaska.
Toward the end of June, a tropical depression moved across the Philippines through the Visayas, first observed on June 26. After moving westward into the South China Sea, the depression turned to the northeast, reaching the Luzon Strait. Later, the depression recurved back to the west, dissipating over China on July 3.
On June 29, a tropical cyclone developed southeast of Palau. It moved to the northwest, remaining east of Palau and the Philippines. Later classified as a typhoon, the system turned to the west and struck Taiwan, then known as Formosa, on July 7. It moved across the island, crossed the Taiwan Strait, and dissipated over China on July 9.
Another tropical depression formed on July 4 near Chuuk. It moved generally to the west-northwest, although it curved southwestward on July 6. The next day, the system passed about 480 km (300 mi) south of Guam, by which time it attained typhoon status. It resumed its movement to the northwest, remaining east of the Philippines. On July 11, a nearby ship reported a pressure of and winds of Force 12 on the Beaufort scale. Two days later, the typhoon passed about 95 km (60 mi) west of Naha, Okinawa into the East China Sea, after turning more to the north. On July 14, the typhoon turned to the northeast into the Sea of Japan, moving between Japan and South Korea. It later crossed Hokkaido, dissipating on July 17 in the Sea of Okhotsk.
On July 8, the Australian Associated Press reported that there was a typhoon about 195 km (120 mi) east of Samar. The storm dropped heavy rainfall over a period of a week, the most since 1919 in one area, which caused river flooding and one death. On July 12, local newspapers also reported a typhoon striking Seoul, South Korea, killing 52 people and leaving thousands homeless. However, neither of the two storms were mentioned in the Monthly Weather Review summary for the month.
A short-lived tropical cyclone appeared on July 11 in the South China Sea, but dissipated the next day. Another short-lived system developed on July 13 near Yap, dissipating on the next day. A few days later on July 18, a tropical cyclone formed west of Guam; the system moved westward and was no longer observed by July 23.
On July 12, a tropical depression formed to the east-southeast of Guam. It moved westward, passing through the Marianas Islands on July 14. Around July 18, the storm turned toward the north, passing east of Taiwan. Three days later, the storm approached the Japanese island of Ishigaki 100 km (60 mi) to the west, where a pressure of confirmed the system attained typhoon status. On July 23, the typhoon turned to the northeast and moved across the Korean Peninsula. The storm turned to the east, later moving across northern Honshu on July 24, and dissipating two days later.
Another tropical depression formed east of Guam on July 21. It tracked westward, passing near the island on July 23, and later shifted more to the west-northwest. On July 26, a ship reported a low pressure of , indicating that the system was a typhoon. The system later passed between the Philippines and Taiwan as it entered the South China Sea, but no land areas reported strong winds, suggesting the typhoon was either very small or had weakened from its peak. On July 29, the typhoon made landfall between Hong Kong and Shantou in southeastern China, quickly dissipating.
On July 24, a tropical depression appeared east of Guam, and soon after passed near the island while tracking northwestward. The system eventually passed between Okinawa and Taiwan, reaching a position 100 km (60 mi) southwest of Naha, Okinawa on July 30; a station on the island reported a pressure of , suggesting the storm attained typhoon status. By the next day, the storm was no longer being tracked in the East China Sea, although the Monthly Weather Review summary indicated that the typhoon continued to the northwest, attaining a pressure of . The storm reached a position northeast of Shanghai and dissipated on August 4 after crossing the Shandong Peninsula.
August
Activity in August began when a tropical depression formed on August 1 to the west of Guam. It exhibited a parabolic track, moving west-northwestward before turning to the south, ultimately dissipating on August 4; it never intensified beyond tropical depression status. Another short-lived tropical depression formed on August 1 near Guam, dissipating on August 3 after having moved to the north and west.
On August 11, a tropical cyclone appeared east of Luzon. Over the next few days, it moved across the Philippines, passing near the island of Mindoro on August 13. The system moved across the South China Sea, intensifying into a typhoon as it approached Vietnam. Although it paralleled the coast, the system dissipated over the Gulf of Tonkin on August 17.
A tropical depression formed on August 13 to the southwest of Guam. It gradually strengthened while tracking west-northwestward, becoming a typhoon on August 16. Two days later, the storm passed near or over northeastern Luzon and moved into the South China Sea. After approaching Hong Kong, the typhoon turned to the west-southwest, paralleling the southern China coast. Although the track for the storm ended on August 22, the Monthly Weather Review summary indicated that the typhoon crossed Hainan. The storm then moved across the Gulf of Tonkin and dissipated on August 25 over Vietnam. In Luzon, stations reported a minimum pressure of in Palanan, Isabela. The storm produced widespread flooding in Luzon, which damaged crops and cut communications, and killed nine people. In Ilocos Norte, the typhoon caused a shipwreck, although the passengers and crew were rescued. Later, the typhoon brought gusts of 134 km/h (83 mph) to Hong Kong.
A short-lived tropical depression formed east of Guam on August 14, dissipating a day later. The next tropical system developed about 565 km (350 mi) north of Yap on August 19. It moved generally to the northwest, interrupted a brief turn to the northeast before resuming its trajectory. It quickly intensified into a typhoon, and Naha, Okinawa reported a pressure of on August 23. After passing near the island, the typhoon turned sharply to the northeast. It moved along the southern coast of Japan before coming ashore west of Tokyo on August 26. Soon after, the storm reached open waters and later passed over eastern Hokkaido, dissipating on August 28.
On August 21, a tropical depression formed near Yap. After moving erratically to the south and northwest, the system dissipated on August 25 to the east of the Philippines. There was another short-lived depression on August 28 to the east of Guam, dissipating a day later.
Another tropical depression formed on August 24 to the east-southeast of Guam. After passing south of the island, the system maintained a steady west-northwest trajectory and quickly intensified into a typhoon. On August 29, the storm passed east of the Batanes islands that are between Taiwan and Luzon; a station there recorded a pressure of . A day later, the typhoon made landfall in northern Taiwan, and after crossing the island, moved ashore in southeastern China near Fuzhou with a pressure of . The storm remained distinct over land, turning to the northeast and passing west of Shanghai. On September 3, the system dissipated off the south coast of South Korea.