The 2018 Pacific typhoon season was at the time, the costliest Pacific typhoon season on record, until the record was beaten by the following year at that time. The season was well above-average, producing twenty-nine storms (including one that crossed over from the Eastern/Central Pacific), thirteen typhoons, seven super typhoons and six Category 5 tropical cyclones, the first such occurrence since 2014. The season ran throughout 2018, though most tropical cyclones typically develop between May and November. The season's first named storm, Bolaven, developed on January 3, while the season's last named storm, Man-yi, dissipated on November 28. The season's first typhoon, Jelawat, reached typhoon status on March 29, and became the first super typhoon of the year on the next day.
The scope of this article is limited to the Pacific Ocean, to the north of the equator between 100°E and the 180th meridian. Within the northwestern Pacific Ocean, there are two separate agencies that assign names to tropical cyclones, which can often result in a cyclone having two names, one from the JMA and one from PAGASA. The Japan Meteorological Agency (JMA) will name a tropical cyclone should it be judged to have 10-minute sustained wind speeds of at least 65 km/h (40 mph) anywhere in the basin, while the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) assigns names to tropical cyclones which move into or form as a tropical depression in their area of responsibility located between 135°E and 115°E and between 5°N and 25°N regardless of whether or not a tropical cyclone has already been given a name by the JMA. Tropical depressions that are monitored by the United States' Joint Typhoon Warning Center (JTWC) are given a number with a "W" suffix.
Seasonal forecasts
During the year, several national meteorological services and scientific agencies forecast how many tropical cyclones, tropical storms, and typhoons will form during a season and/or how many tropical cyclones will affect a particular country. These agencies included the Tropical Storm Risk (TSR) Consortium of University College London, PAGASA and Taiwan's Central Weather Bureau. The first forecast of the year was released by PAGASA on January 15, within its seasonal climate outlook for the period January–June. The outlook noted that one to three tropical cyclones were expected between January and March, while two to four were expected to develop or enter the Philippine Area of Responsibility between April and June. PAGASA also mentioned that the La Niña would be short-lived, predicting that it would last until February or April.
On March 15, the Vietnamese National Center for Hydro Meteorological forecasts (VNCHMF) predicted that roughly twelve to thirteen tropical cyclones would affect Vietnam during 2018, which is above average. On March 23, the Hong Kong Observatory predicted that five to eight tropical cyclones would come within 500 kilometres of Hong Kong, which is normal to above normal, with the first tropical cyclone affecting Hong Kong in June or earlier. On May 11, the Tropical Storm Risk (TSR) issued their first forecast for the season, predicting that the 2018 season would be a slightly above average season with 27 named storms, 17 typhoons, and nine intense typhoons. The TSR released their second forecast on July 6, still predicting that the season will be above average, with the only changes to their forecast increasing the number of intense typhoons from 9 to 10. The PAGASA issued their second and final outlook on July 13 for the period of July – December, predicting six to eight tropical cyclones were expected to develop or enter their area of responsibility between July and September, while four to six were forecast during October to December. On August 7, TSR released their final forecast, with its only changes decreasing the numbers of intense typhoons from 10 to 9, as well as decreasing its ACE forecast from 331 units to 319 units.
Season summary
2018 opened with Tropical Depression Agaton active to the east of the Philippines. Over the course of two days, the system moved into the South China Sea and intensified into the first named storm, Bolaven. A month later, Tropical Storm Sanba developed and affected the southern Philippines. About another month later, Tropical Depression 03W formed in the open Pacific and was named Jelawat. Jelawat intensified into the season's first typhoon on March 29, and then the season's first super typhoon. Tropical activity fired up by June, when a series of storms developed, with Tropical Storm Ewiniar making landfall over mainland China. Later that month, Typhoon Prapiroon developed and affected the Korean Peninsula, becoming the first to do so since 2013. Thereafter, Typhoon Maria developed and reached its peak intensity as a Category 5 super typhoon, being the first typhoon to reach that intensity since Typhoon Nock-ten in 2016. Hurricane Hector crossed the International Date Line on August 13, the first to do so since Genevieve in 2014. Systems like Tropical Storms Son-Tinh, Ampil, Josie, Wukong, Jongdari, Shanshan, Yagi, Leepi, Bebinca, and Rumbia formed between late July and early August.
On August 16, Typhoon Soulik developed and headed north, until a Fujiwhara interaction with Typhoon Cimaron (which formed after Soulik) made it head west towards the East China Sea. It later made landfall on South Korea, making it the first typhoon to make landfall on South Korea since Typhoon Chaba in 2016. Cimaron made landfall near Kyoto, Japan on August 23. As Cimaron was nearing landfall, Tropical Depression Luis formed, which made landfall on China and Taiwan. Later that month, Typhoon Jebi developed over the West Pacific and intensified into the third super typhoon of the season.
In September, Typhoon Mangkhut became the fourth super typhoon of the season and made landfall on the island of Luzon in the Philippines. On the same day, Tropical Depression Neneng formed, which later became Tropical Storm Barijat and made landfall on Vietnam. By late September, Typhoon Trami (Paeng) formed, becoming the 5th super typhoon of 2018. While Typhoon Trami was in the Western Pacific, nearing Okinawa with winds of 165 km/h (103 mph), Tropical Depression 30W formed, and was named Kong-rey by the JMA after strengthening into a tropical storm. It intensified into a super typhoon on October 2, becoming the 5th Category 5 super typhoon. Later on in the month, it was followed by the sixth and final Category 5-equivalent storm of the season, Yutu.
Systems
Tropical Storm Bolaven (Agaton)
A low-pressure area developed into a tropical depression northeast of Palau on December 29, 2017. The system moved generally westward, and on the first day of 2018, the PAGASA began issuing advisories on the system and locally named it Agaton. Both the JMA and the JTWC followed suit, with the latter designating the system as 01W. The depression reached the Philippines on January 1, making landfall over Bucas Grande at 17:00 UTC, then at Claver, Surigao del Norte at 17:15 UTC. The system crossed the Bohol Sea before making a third landfall near Jagna, Bohol at 20:00 UTC, a fourth in Santander, Cebu at 21:00 UTC, and a final landfall at Bais, Negros Oriental at 23:30 UTC. By January 3, the system had intensified into a tropical storm according to the JMA and was named Bolaven, thus becoming the first named storm of the season. However, several hours later, Bolaven started to weaken and rapidly deteriorate. The system was last tracked by the JMA to the east of Vietnam on January 4.
The impact caused by Bolaven (Agaton) was moderate but not as significant as the previous two systems, Kai-tak and Tembin, with about 2,000 passengers stranded in ports in the Visayas. As of January 22, three people have been reported killed by the storm, while total damages were up to Ph₱554.7 million (US$11.1 million).
Tropical Storm Sanba (Basyang)
A low-pressure system developed into a tropical depression north of Chuuk early on February 8. It developed into a tropical storm on February 11, receiving the international name Sanba by the JMA. Shortly afterwards, Sanba entered the Philippine area of responsibility and was assigned the local name Basyang by the PAGASA. On February 13, Sanba made landfall on Cortes, Surigao Del Sur, causing it to weaken to a tropical depression. On the next day, the system weakened into a remnant low as it made another landfall in Surigao del Sur.
A total of 1,660 houses were damaged, of which 429 were completely destroyed; most of the homes damaged were in Caraga. Siargao Island, Silay City, Carmen municipality in Bohol, and the municipalities of Culaba and Kawayan in Biliran were affected by power outages from February 12 to 13. Twenty-two roads and eight bridges were damaged by floods and landslides. Two boats carrying people capsized: a fishing boat near Silago, Southern Leyte, and a passenger vessel en route to Homonhon. All four on board the two boats survived. Approximately 17,000 people were affected by the storm and there were 14 fatalities. Total agricultural damages were at Php 168 million (US$3.23 million), mostly coming from flooded rice fields.
Typhoon Jelawat (Caloy)
On March 24, a tropical depression formed to the south of the Mariana Islands, and the JTWC assigned it the numerical identifier 03W. On March 25, the system intensified into a tropical storm and was named Jelawat by the JMA, and at the same time it entered PAGASA's Philippine Area of Responsibility (PAR) and was assigned the local name Caloy. Due to strong southwesterly wind shear, the cyclone remained poorly organized, with disorganized convection near an exposed low-level circulation. Conditions gradually became more favorable for further development, resulting in Jelawat steadily strengthening and gaining organization before intensifying into a severe tropical storm at 18:00 UTC on March 28. Later on March 29, an eye began to emerge within a growing central dense overcast, leading to the JMA classifying it as a typhoon at 00:00 UTC on March 29. Explosive intensification then ensued over the following 36 hours as the eye became sharply defined, and Jelawat attained its peak intensity later that morning, with estimated 10-minute sustained winds of 195 km/h (121 mph) and a central pressure of 915 hPa (27.0 inHg). At the same time, the JTWC assessed it as peaking with 1-minute sustained winds of 240 km/h (150 mph), making it a Category 4 super typhoon.
Immediately after peaking in intensity, Jelawat began weakening rapidly due to a sharp increase in wind shear and dry air, and the storm fell below typhoon strength late on March 31. During the next couple of days, Jelawat drifted to the northeast and then turned eastward before dissipating on April 1.
Jelawat yielded 20 inches of rainfall on parts of the island of Pohnpei, resulting in flooding and landslides that caused critical damage to infrastructure and one death. A woman in Guam drowned from the remnants of Jelawat on April 3, after strong surf and rip currents stranded her in water.
Tropical Depression 04W
A low-pressure area east of Mariana Islands was upgraded to a tropical depression by the JMA late on May 10 shortly before the JTWC issued a TCFA. By May 12, deep convection was observed near its center as the JTWC began issuing advisories on the system, giving it the designation 04W. Roughly twelve hours later, it was reported that 04W had intensified into a tropical storm by the JTWC after satellite imagery had depicted a well-defined center. Tracking on a west-northwesterly course, the system began to weaken as it entered an area of unfavorable conditions. 04W rapidly weakened as the JTWC issued their final advisory on the system early on May 14 as wind shear affected the system and exposed the elongated low-level circulation. The JMA, however, tracked the system until early on May 15, when it dissipated.
Tropical Storm Ewiniar
A low-pressure area developed into a tropical depression over the South China Sea on June 2. Later that day, the JTWC followed suit and assigned the designation 05W to the system. 05W meandered in a westward direction until it curved northward, and after three days, the JTWC upgraded the system to a tropical storm. The JMA did the same three hours later early on June 6, naming it Ewiniar. Shortly thereafter, Ewiniar made landfall over South China. Ewiniar maintained its intensity while over land until the JTWC issued its final advisory late on June 7. The JMA, however, tracked the system until early on June 9, when Ewiniar had weakened into a tropical depression and degenerated into a remnant low. However, Ewiniar's remnants moved out to sea and continued to persist, before dissipating on June 13.
A total of 13 people were killed, while total damages in mainland China were counted to be ¥5.19 billion (US$812 million).