The decade of the 1940s featured the 1940–49 Pacific typhoon seasons. The seasons 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.
A short lived system, the IBTrACS database contains only three 6-hour positions on the western side of the Philippines.  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 briefly reached Tropical Storm strength. 
Monthly Weather Review for April 1940 describes this as a depression of minor importance which formed near the western Carolina Islands. It moved westward passing close to and south of Yap before dissipating.  The Historical Weather Map shows the system as a Tropical Storm (winds between 34 and 64 knots) from April 11 to April 13 before disintegrating into a low pressure area west of Luzon in the Philippines.
Described in Monthly Weather Review as a "typhoon, violent over a small area" that passed across northeast Mindanao. Towns along the eastern and northern coast experienced strong winds for a short time and heavy rains. On April 26 the ship S.S. Tjieboet from a position near 8 30' N 127 00' E reported winds of force 10 to 12 and a pressure of 738.8 mm (985.0 mb). Three lives were reported lost when the motorboat Fookien sank near 8 38' N 126 05'E.
The Historical Weather Map shows a depression near 7 N 143 E on April 21 and a Tropical Storm between April 22 and April 23. Thphoon winds were analyzed between April 24 and 27 as the system crossed into the South China Sea. By April 29, only a broad low pressure area remained near 8 N 113 E. 
Monthly Weather Review describes this cyclone as a Typhoon first noted 300 miles east of Yap on June 10, 1940. Performing an anti-cyclonic loop near 17 N 132 E the system was tracked to the south of Japan where it apparently underwent extratropical transition. No loss of life was reported from Japan with this system.  Historical Weather Maps are not available for June of 1940 so no further description is available. 
Historical Weather Maps for July 1, 1940 shows a Tropical Storm near Hong Kong at 22 N 114 E. The system moved inland and was last analyzed near 23 N 104 E on July 3. This system is not mentioned in Monthly Weather Review nor is it included in the IBTrACS archive. The lowest pressure reported was 993 mb from a ship on July 1 some distance from the system. 
IBTrACS database first shows this system near 4.4 N 140.6 W on June 29, 1940. Moving in a northwest direction, the system crossed Taiwan on July 6 and entered mainland China early the next day. This system is (apparently, there is some question with the identity of the system) discussed in Monthly Weather Review as a typhoon between July 2-9. The lowest pressure reported was from an island station on July 7 of 739.7 mm (986.2mb). Historical Weather Maps are unavailable for June 1940 but July opened with the system designated as a typhoon, an intensity maintained until landfall. Tropical Storm strength was maintained on July 9 near 28 N 114 E. and the residual low was last seen at 30 N 109 E. 
This typhoon formed south of Guam, reaching Tropical Storm winds by July 7 and Typhoon category the next day. The storm traveled west then northwest recurving into the Sea of Japan. The steamship Coldbrook reported a pressure of 719.3 mm (959.0 mb) July 11 near 21.6 N 128.5 E. Weakening back to Tropical Storm strength on the 14th, the storm experienced extratropical transition between July 15 and 16. 
Tropical Cyclone Nine formed southeast of Guam reaching Tropical Storm strength on the 13th and typhoon strength on the 15th. Recurving on the 21st, landfall was in Korea as the system rapidly moved over the Sea of Japan. An island weather station, located about 60 miles east of the typhoon reported a presssure of 739.0 mm (985.3 mb). On the 26th of July, the system interacted with a frontal system near northen Japan and was absorbed. IBTrACS tracks the extratropical low eastward to near 160 E.
Tropical Cyclone Eleven is included in the IBTrACS data base and is on the Historical Weather Map, but is not described in the July 1940 issue of Monthly Weather Review. On July 17, 1940 a low pressure area was analyzed southwest of Tropical Cyclone Nine which quickly developed into a tropical storm near 15 N 142 E. The storm trailed Nine but never developed, possibly due to outflow from Typhoon Nine. By the 21st, the system fell below Tropical Storm strength west of the Philippine Islands.
Tropical Cyclone Twelve formed as Eleven weakened. Moving northwest, it passed between the Philippines and Taiwan entering mainland China near Hong Kong. It was a very strong typhoon and shown by an observation from the steamship Kujawa Maru near 18 20' N 124 30'E of a pressure of 695 mm (926.6 mb). The storm weakened but was still analyzed as a Typhoon at landfall. Following landfall, the system began to recurve, moving northward as a tropical storm near 26 N 117W on the 29th and a disorganized low the next day.
Cyclone Thirteen is found in the IBTrACS database is described in Monthly Weather Review. On July 26 a low pressure area was analyzed near 15 N 142 E that grew to a Tropical Storm on the 27th and a Typhoon on the 28th. There are significant differences between IBTrACS which loses the system near 29N 124W and the Historical Weather Maps which show the weakened Tropical Storm moving north along the China coast. August 3 finds the system absorbed with a cold front near 40 N 120 W. The lowest pressure reported in Monthly Weather Review was from the City of Norfolk of 729.8 mm (973 mb)
Tropical Cyclone Fourteen is described in Monthly Weather Review as a "depression, apparently of minor importance" which formed between the Philippines and the Mariana Islands. Historical Weather Maps tracks the depression as it turned northward on August 4 and continued until August 5. However, this recurvature is not reflected in the IBTrACS database and track has the system remaining near latitude 15 N. The system was last seen on the 4th south of Japan. 
Tropical Cyclone Fifteen is identified in IBTrACS south of 30 N. near 140 E. but is not described in Monthly Weather Review and is not identified on the Historical Weather Map. This was about 15 degrees north of Cyclone 14 and may represent the same system. 
Of three low pressure systems across the West Pacific on August 11, this was the farthest west and would develop into a Tropical Storm by August 13. Taking a Northwest track, Historical Weather Maps upgrade the system to a Typhoon on the 15th. Between the 18th and 19th, the typhoon crossed between the Philippines and Taiwan then continued west northwest toward mainland China. By the 23rd, Historical Weather maps shows a Tropical Storm which crossed northern Vietnam before it dissipated on the 25th.
The Royal Observatory at Hong Kong reported a minimum pressure of 29.215" (989 mb) and estimated the central pressure of 28.8' (975 mb). However it appears the system was significantly stronger when located in the Pacific Basin. Nine lives were reported lost in central Luzon from this typhoon as large areas were flooded. The Steamship Nanyo Maru was wrecked and totally destroyed but all passengers and crew were rescued. 
The system developed east of Taiwan. It moved in a northeastward direction and it finally dissipated on the 5th. It is unknown weather the storm's peak strength was at a strong tropical depression or weak tropical storm. The storm affected the Ryukyu Islands.
The final storm of the season developed on December 13 east of Mindanao, Philippines or in the Philippine Sea. It moved in a fast, northward direction. On the 15th, it moved west, and then west the next day. It finally dissipated early on the December 17, due to vertical windshear.
On January 16, the remnants of a weakening cold front to the east of the Philippines spawned an area of low pressure. The system became better organized as it moved to the northeast, however remained rather shallow. The low was absorbed by a cold front advancing from the north early on January 18, just to the north-northwest of Guam. Based on data from Chin's Atlas the system achieved typhoon strength between the 16 and the 18 of January, however historical weather maps indicated the system never strengthened to a tropical storm.
A tropical low formed to the southwest of Guam and west of Palau on April 8. It moved westward over the next few days and continued to gradually deepen. Discrepancy in the location and strength of the system between Chin's Atlas and weather maps makes it difficult to pinpoint where the system went to after this point. The Chin's Atlas data set has the system moving to the north of Palau and eventually dissipating to the northeast of Catanduanes as a tropical storm on April 16. Historic weather maps has the low moving straight west towards Mindanao, and curving sharply to the north on the 13. Afterwards the low strengthens to a tropical storm while paralleling the coast to the east during April 14. On April 15 the storm made landfall in Eastern Samar with a pressure below 1000 millibars. Afterwards the storm weakened and moved north in response to a nearby front and stalled to the east of Luzon. An area of low pressure soon evolved to the north near Taiwan, on April 18, and moved the stalled depression to the north east. Later the system became absorbed with a cold front.
Chin's Atlas has a tropical storm moving to the northwest of the Mariana Islands between the 15 and 16 of April. Weather maps indicate a weak low pressure area attached to a cold front, likely indicating the storm was extra-tropical in nature. The remnants of the storm was located several miles south of Japan.
A storm developed in the Philippine Sea and east of Visayas, Philippines on May 11. It strengthened into a typhoon during its lifecycle but it is unknown of where it reached its intensity. The storm finally dissipated on May 21.
A small, yet powerful typhoon, Connie, was first spotted on June 1 by the Weather Central Guam, moving northeast. Winds were reported to have been as high as 140 mph. But by June 7, it began to weaken. Its final fate is unknown. The US Navy's Fifth Fleet (formerly Third Fleet) was hit by Connie. The same fleet had previously been hit, with great loss of life, by Typhoon Cobra, in 1944. Connie being lesser, only one officer and five USN men were lost or killed because of Connie, and around 150 airplanes on its carriers were either lost or damaged.
Typhoon Helen formed on August 29. It moved west-northwest and strengthened into a category 3 typhoon with 120 mph winds. It weakened slightly to a category two and struck Taiwan. It briefly was over waters before it hit China as a tropical storm. It dissipated on September 4.
This typhoon is especially remembered for the 30 aircraft containing liberated prisoners of war brought down by the typhoon between Okinawa and Manila. Over 900 servicemen lost their lives. It is the single greatest loss of life in an aviation disaster during peacetime.
Louise was first seen developing on October 2, 1945 in the Caroline Islands. It unexpectedly veered north and slowed down, only to intensify as it passed over Okinawa on October 9 with 90 mph wind gusts and a minimum central pressure of 968.5 mbar. Shortly after, Louise began to weaken, and hit Japan as a strong tropical storm. The tropical cyclone became extratropical shortly after on October 12. In Okinawa, 36 people died, 47 people were reported missing, and 100 people were seriously injured. In Buckner Bay, the US military were occupying a temporary base. 30 ft (9.1 m)–35 ft (11 m) waves were reported to have crashed ashore, tearing into their Quonset huts and other building. The Bay was being used as port for the US military. Fifteen merchant cargo ships were grounded, with a few unrecoverable. 3 US Navy Destroyers were grounded beyond salvage, and over 200 various other US military boats, including 6 tank and truck amphibious landing craft, a number of special purpose boats, patrol boats, and amphibious landing craft were grounded or severely damaged, and beyond. Eighty percent of the buildings in the bay were completely wiped out while all 60 airplanes at the local airports were damaged.
Typhoon Barbara formed on March 27, and moved west. It strengthened briefly to a category three with 115 mph winds. But shortly after, it began to weaken. Typhoon Barbara curved northward and then westward, in turn hitting the Philippines as a category one. After making landfall, it curved back to the east and continued to weaken until April 7, when it dissipated.
On June 17, Typhoon Dolly formed. It moved northwestward, only to strengthen. After passing by the Philippines, it reached its maximum intensity of 125 mph, a strong major hurricane. It rounded around Taiwan and made landfall on China's shoreline. It dissipated hours after on June 23.
Tropical Storm Ingrid formed July 12, immediately moving west. After strengthening, it briefly became a category four on July 15. It weakened to a category two and struck the northern part of the Philippines. Ingrid retained its strength until it hit China. Right after it made landfall in China, it moved north and dissipated on July 20.
Janie formed on July 23. It moved northwest and then curved west. It was then that she became a major hurricane with 115 mph winds. After heading westward for a while, Janie began curving the opposite direction. But that was short-lived; it began moving northwest and struck southern Japan. Janie traveled over the island and dissipated near Russia's coast on July 31.
On August 10, a disturbance managed to organize itself enough to be designated Tropical Storm Lilly. It moved in a generally northwest direction while intensifying at a moderate pace-becoming Typhoon Lilly shortly after its formation. Before Lilly moved over cold waters, it attained a peak intensity of 145 mph. It narrowly missed Japan's shoreline as a category two before striking Korea as a moderate tropical storm. Lilly dissipated on August 21, after eleven days of the traveling of the western Pacific Ocean.
Carol formed east of the Philippines on June 17. It moved northwest and skimmed right past the most northern island as a 115 mph typhoon. After that, it began to weaken. Carol passed by Taiwan, and was about to hit mainland China, but it suddenly took a northeast track. Shortly thereafter, Carol dissipated on June 23.
The Joint Typhoon Warning center (JTWC) best tracks lists this system as 03W.
Typhoon Kathleen struck the Boso Peninsula and the entire Kanto Region in Japan on September 15. Heavy rains caused the Arakawa and Tone Rivers to overflow. The resulting floods killed 1,077 people and left 853 people missing.
The origins of Rosalind can be track on a tropical storm that intensified into a category 2 on October 6 and named Rosalind. Therefore, Rosalind continued to rapidly intensify from 964 to 918 mbar, reaching its peak intensity. After Rosalind reaches its peak intensity, slight wind shear causes Rosalind to weaken on a category 2 on October 10. It intensified into a category 3 before it moved slowly. It weakened to a category 1 and tropical storm. Rosalind dissipated on October 14.
Rosalind was the first super typhoon ever recorded in the Pacific Ocean.
Tropical Storm Irene formed on November 30 between the Philippine Islands. It strengthened to a tropical storm with 50 mph winds before it made landfall on one of the islands. It curved northeast and weakened to a tropical depression. But after exiting land, it restrengthened to a moderate tropical storm. But shortly thereafter, it became extratropical on December 3. The Japan Meteorological Agency analyzed it as a tropical depression, though it was actually a moderate tropical storm.
Typhoon Karen, the strongest cyclone of the season, developed on January 11, well west of the Philippines. It curved westward while slowly intensifying. After a prolonged period of the slow intensification, the tropical cyclone began to rapidly strengthen. It became a super typhoon on January 16. Shortly after, it weakened and dissipated on January 19.
Ophelia formed on June 10 in the South China Sea. It moved west and struck southern China. It dissipated the next day, without attaining maximum sustained winds any higher than 45 mph.
Typhoon Ione struck Japan in mid-September killing 838 people.
Tropical Storm Dolores was tracked by the Air Weather Service located on Guam. At one point, a tropical storm was identified and assigned the name Eunice. Post analysis showed that Tropical Storm Dolores was north of the forecast location and actually the system assigned the name Eunice.
Between 23 July and 4 August, the name Annabell was assigned to a North West Pacific system. The Air Weather Service issued a bulletin issued and tropical cyclone named on what was later determined to be "trough activity”
Typhoon Della struck Japan in mid-June killing 468 people.
In July, tropical storm Irma killed 1,600 people and destroyed more than 63,000 houses in Shanghai, China, the worst typhoon on record in the city.
Typhoon Gloria struck Okinawa on July 23. Gloria killed 38 people and destroyed 42,502 buildings on the island. Typhoon Gloria then continued westward and struck Shanghai, China killing 29 people.
Typhoon Kitty struck the Tokyo/Yokohama area August 31 through September 1, 1949. From reconnaissance reports the maximum sustained winds were near 110 knots 12 hours prior to landfall, but had fallen to minimum typhoon strength by the time it reached Honshū. The death toll reached 123 due to rainfall induced flooding and landslides (NY Times, 9/3/1949), and caused about 15 billion yen in damages. As its center passed near Tokyo, the JMA's Central Meteorological Office was able to launch eight rawindsondes in the typhoon environment. Researcher Dr. Hidedoshi Arakawa was able to analyize these soundings to make a vertical analysis of the storm.
Carmen's origin was traced to the southeast of Yap, at the junction of the base of a westerly trough and a secondary line of convergence associated with the Inter-tropical trough. It's track was followed south of Yap and northwest between Yap and Palau. Much speculation was afforded when three reconnaissance fixes indicated a loop in Carmenn's path. Indications were that Carmen was a veery small storm in the respect that high winds and weather extended only a short distance from it's center. An allowance for navigational error along with a 48 hour stagnation would have discounted the unusual recurvature. The final leg pursued a southwest course into Mindanao, the result of theSiberian high cell's intrusion into the Philippine Sea.
Della began as an easterly wave and can be traced as far east as Truk with consistence. Kwajalein shows the passage also, but its track to Truk is indistinct. The eventual track was substantiated by data at Guam and Yap with intensification evident near 15 N and 127 E, seven days after the easterly wave passage at Truk. A surge of moist unstable air from the south was considered as the primary factor in intesification. A parabolic path was followed, with the eye passing over Okinawa. Contrary to climatological data, Della pursued a path across Kyishi rather than the conventional movement along the polar trough to the south of Japan. Della moved into the Sea of Japan and became extratropical four days after it was detected as a typhoon 
Elaine developed from an ill-defined easterly wave that passed south of Guam. Lack of sufficient data prevented accurate detection of the easterly wave east from Guam. As Elaine passed Yap, a surge of the monsoon winds to the south of the Inter-tropical trough intensified the wave and a weak circulation developed. The tropical storm moved at 12 knots until it passed over the northern tip of Mindanao; from this point a gradual recurvature toward the northwest was taken. A southerly flow in the South China Sea aided the intensification. The storm tracked within 60 miles of Manila and dissipated rapidly as it entered the China coast west-southwest of Hong Kong.
Faye was one of two storms that had its origin in the upper air, between 25 and 40 thousand feet, and gradually descended to the surface over the western edge of the Pacific high cell(indications of Kwajalein's upper winds verified the presence of an upper air low, and five days later it's nearness to Iwo Jima was reflected on the surface) Faye, a moderate storm moved near and to the south of Iwo Jima and recurved around the Pacific high cell, 500 miles to the west of Iwo Jima. Faye followed a northerly path and passed over the western edge of Kyushu into the Japanese Sea. 
Gloria, one of the most intense and destructive typhoons of the 1949 season, formed from a vortex associated with an easterly wave which was intensified by a southwesterly monsoon surge after passing south or Guam. Gloria was first detected as a typhoon near 15 N. and 132 E. Her future track was north for 450 miles with curvature to the northwest passing over Okinawa and entering the China coast near Shanghai. Maximum winds were estimated in excess of 110 knots. 
Hester was one of the season's most confusing storms, resulted from the intensification of an easterly wave near Guam. Post analysis indicates that a convergent westerly and southwesterly flow in the vicinity of Saipan was the factor in intensification. Reconnaissance revealed a loop in Hester's track near Saipan. After a north-northwesterly movement to the east of Iwo Jima, the storm finally entered the Japanese mainland to the south of Tokyo. Hester was strongest at the time she was first detected and weakened thereafter, becoming negligible when it struck the Japanese islands.
Irma originated in the South China Sea and intensified into a weak storm for reasons that are only supposition due to a lack of data in that area. Her path was northeast and finally north. Throughout her life, reconnaissance could find no evidence of a defined center, but reported 50 knot winds.
Judith, began as a vortex associated with an easterly wave and can be identified as having passed Kwajalein 20 days prior to its dissipation. Intensification into a typhoon occurred near 14 N and 126 E but the reason is uncertain. Soon after detection of the typhoon, normal recurvature began, but two days later an inverse recurvature was evident. At the time it was thought that Judith split into two cells one moving east-northeast and the other north-northwest. Post analysis indicates that only one cell was present and it's path was slightly to the east of Okinawa with inverse recurvature over western Kyushu 
Kitty originated from an easterly wave that passed Kwajalein and intensified near 23 N and 15.4 E It is believed that intensification was the result of a westerly trough that moved to the. north of the storm prior to its detection. Further, the northwest movement into the nose of the Pacific high cell assisted in maintaining the gradient. Kitty began recurvature near 32 N and 140 E, but was never completed as the storm maintained a northerly movement across Honshu and dissipated near Hokkaido. Reconnaissance reported a maximum wind of 65 knots. Kitty inflicted more damage on the Tokyo area than any storm during the 1949 season. Gusts to 75 knots were reported along with torrential rains. 
Tropical Cyclone Lise was first detected as a weak topical low passing north of Guam and Saipan on 31 August, Navy Reconnaissance two days later established that this low had increased to typhoon intensity. Intensification is attributed to the low moving into a stagnant low pressure area in tho Philippine Sea. Lise began a sharp recurvature on 2 September and passed 70 miles southeast of Iwo Jima as an intense typhoon on 4 September. Maximum winds of 85 knots were experienced at Iwo Jima for a short period. 
Madeline was the second of two storms during the seasor that originated in the upper air and surfaced over the western edge of the Pacific high cell A surface ship. on 2 September fist gave indications of a relatively weak storm in the vicinity of 21 N and 151 E. The storm was discovered, while in the process of recurvature; the track thereafter moving northward while missing Iwo Jima by 450 miles. Madeline dissipated into polar trough five days after it was detected. 
Nelly was the result of an easterly wave that intensified into a typhoon eight days after it's passage at Truk. The factor in intensification was a weak but persistent westerly trough that extended south-southwest to a point just northeast of the storm. Reconnaissance established Nelly as a typhoon 250 miles south of Okinawa, after three previous missions over a period of five days had failed to find winds in excess of 45 knots. The storm passed south of Okinawa and struck central Formosa. Nelly disappeared into the China coast north of Hong Kong. 
Omelia was first noticed in the latter days September in the Yap-Palau area. This storm can be traced to Kwajalein, nine days prior to its intensification to a tropical storm. Data is insufficient to determine the cause of intensification, and reconnaissance fixes failed to reveal its intensity. Moving northwest-ward, Omelia passed between Luzon and Taiwan striking the China coast on 4 October 180 miles northeast of Hong Kong. Omelia's distinguishing feature was the reported fact that no closed circulation could be found near the center by reconnaissance. 
On 17 October, surface ship reports from the Truk area gave the first indication of the tropical disturbance later named Patricia. As it moved slowly northwestward it began to intensify such that a definite closed circulation was apparent with the passage-southwest of Guam on 20 October. At this time, the storm' was in the process, of recurvature and continued thereafter on a northeasterly track which skirted all U.S. Military installations. Patricia traversed over 3,000 miles in the eleven days it was under surveillance. 
Tropical Storm Rena was an example of the early winter storms which form and intensify in the Palau area, then move across the Southern Philippines to die in the south China Sea. Rena passed through the islands bringing heavy rains but not excessive winds. It is thought that damage was slight since the maximum winds reported by a land station was 45 knots. Rena took up a course for Hong Kong, but dissipation had already begun, and in crossing the China Sea the storm lost its identity. 
On 10 November, Kwajalein experienced the first effects of a storm which later developed into Typhoon Allyn. The torrential rains and a wind shift indicative of a vortex induced the Kwajalein forecaster to release a tropical advisory (TROPAD) alerting the Typhoon Warning Network. As the storm continued to move westward it rapidly intensified. The first reconnaissance flight established the center of the storm, then north of Truk reported maximum winds of 60 knots. Three days later when the storm approached Guam, the winds had increased to 120 knots. On 17 November, Typhoon Allyn struck Guam with a ferocity unequaled since 1900. Passing within 35 miles of the southern end of the island,the storm created havoc on a grand scale. No lives were lost, even among the natives, who were lacking typhoon shelters, endured the storm in their houses, hundreds of which were completely destroyed. By early morning on the 18th, the populace was able to leave their shelter to survey the destruction which amounted to millions of dollars. Allyn continued along a west northwesterly track apparently headed for Okinawa; however, recurvature occurred, and the typhoon passed south of Japan, lashing Torishima with 80 knot winds before extratropical transition and setting course for the Aleutian low. 
Tropical Cyclone Betty, a small but reportedly intense storm developed in the Yap-Palau area December 2nd and 3rd then moved west northwestward through the South Central Philippine Islands at an average speed of 12 knots. Although the first reconnaissance fix on 03 December estimated the winds at 80 knots, the light surface winds which were reported as the storm moved through the Philippines indicate that Betty probably never exceeded 50 knots intensity. Thus ended one of the weaker and more obscure storms of the season. 
Camilla, the final significant storm of the 1949 typhoon season was the ninth tropical cyclone to intensify in the Yap-Palau area. Similar to other late season storms; Camilla moved west northwestward across the Philippines at an average speed of 12 knots. Here, Camilla departed from the climatological tracks curving northward across northern Luzon, weakening while crossing the mountainous area. Camilla then continued to move northeastward along the polar though, accelerating rapidly and becoming extratropical just east of Okinawa.