2023 Pacific hurricane season

An El Niño year with a violent finish

By every headline measure, 2023 was well above normal in the eastern Pacific. NOAA's 1991 to 2020 averages are about 15 tropical storms, 8 hurricanes and 4 major hurricanes, and the site's archive records 17 tropical storms, 10 hurricanes and 8 major hurricanes, double the usual number of major storms. Accumulated cyclone energy, which combines strength and duration, reached 168.2, well beyond the 80 to 115 range NOAA treats as near normal. Both NOAA and Mexico's weather service had forecast a busy year, and NOAA's May outlook of 4 to 8 major hurricanes proved too low.

The main driver was the return of El Niño, which brought unusually warm sea surface temperatures and low vertical wind shear to the basin and helped fuel a run of storms that intensified very quickly. Most of the activity stayed east of 140°W. No storm formed in the central Pacific for the fourth season in a row, although four systems, including Calvin, Dora and Greg, crossed into it from the east.

A late start, a busy August and a crowded October

The season was slow to get going. Nothing formed in May or most of June, and the first tropical storm observation came only on 27 June, when Hurricane Adrian developed well off southwestern Mexico. Adrian became the season's first hurricane the next day, and Hurricane Beatriz followed within days, skirting the coast of southwestern Mexico before breaking down over the high terrain. The two made June busier than average for hurricanes despite the late start.

July was below normal. Hurricane Calvin became the first major hurricane in mid-month and later drifted into the central Pacific, and a short-lived depression came and went. On the last day of the month Hurricane Dora formed, the start of a much busier August. Tropical Storm Eugene, Hurricane Fernanda, Tropical Storm Greg, Hurricane Hilary and Tropical Storm Irwin followed during the month, and on 16 August Greg, Fernanda and Hilary were all active at once.

September was quieter than normal, with only two named storms, but one of them was Hurricane Jova, which reached Category 5 far from land. Tropical Storm Kenneth and two depressions made up the rest of the month. October was the season's peak: five storms formed, three of them became major hurricanes, four storms struck Mexico, and a fifth brought deadly floods to Central America.

The season then wound down with Tropical Storm Ramon, which drifted over open water far from land in late November. Ramon became a tropical storm at 12:00 UTC on 24 November, the latest date for a new eastern Pacific tropical storm since Hurricane Winnie in 1983, and the archive's last tropical-stage observation of the year comes from Ramon on 26 November.

Eight major hurricanes and two at Category 5

Hurricane Otis was the season's strongest storm, peaking at 145 kt with a minimum pressure of 922 hPa at 03:00 UTC on 25 October, just 50 n mi south-southeast of Acapulco. Its strengthening was extraordinary: the National Hurricane Center estimates Otis gained 90 kt in 21 hours, a rate beaten in eastern Pacific records only by Hurricane Patricia in 2015. It drew on water of 30 to 31°C, about 1 to 2°C warmer than normal for October off southern Mexico.

Hurricane Jova was the season's other Category 5 storm. It went from a 30-kt depression to a 140-kt hurricane in 48 hours, peaking at 00:00 UTC on 7 September with a pressure of 926 hPa, and then weakened over cooler water without affecting land. Hilary showed the same explosive growth a few weeks earlier, rising by 90 kt in 48 hours to a 120-kt Category 4 peak on 18 August.

The remaining major hurricanes all reached Category 3 or 4. Hurricane Dora peaked at 130 kt on 6 August and became the season's longest-lived storm, travelling from the eastern Pacific across the central Pacific and over the International Date Line, where it became a typhoon. It was only the second tropical cyclone on record to cross all three Pacific basins as a hurricane, after Hurricane John in 1994. Hurricane Lidia reached 120 kt, Hurricane Fernanda and Hurricane Norma 115 kt each, and Hurricane Calvin 110 kt.

Landfalls and impacts

Otis struck Acapulco around 06:45 UTC on 25 October as a 140-kt Category 5 hurricane, the strongest landfalling hurricane in the eastern Pacific since the National Hurricane Center took over forecasting for the basin in 1988. Mexico's government reported 52 deaths, with 32 people still missing, and the Hurricane Center warns that the final toll, direct and indirect, could be much higher. Estimates from risk analysis and reinsurance firms put total damage in Mexico at 12 to 16 billion US dollars (2023), making Otis the costliest tropical cyclone on record for the country. More than 51,000 homes were destroyed in Guerrero, over 98% of homes in Acapulco were damaged, and hundreds of boats sank or were thrown ashore in Acapulco Bay.

Otis was the last of three October landfalls in Mexico. Tropical Storm Max came ashore in Guerrero on 9 October, and its flooding caused two direct deaths, in communities that Otis later devastated. Hurricane Lidia made landfall at its 120-kt peak near Las Peñitas, Jalisco, about 35 n mi southwest of Puerto Vallarta, around 00:00 UTC on 11 October, causing three direct deaths in Jalisco, Nayarit and Colima. Jalisco's governor put state damage at 77.6 million US dollars (2023), a figure the Hurricane Center calls likely incomplete. Hurricane Norma hit Baja California Sur near El Pozo de Cota as a 70-kt hurricane on 21 October and reached Sinaloa as a depression two days later, dropping up to 19.21 inches of rain and causing three indirect deaths in Sinaloa.

Hilary had weakened to a 50-kt tropical storm by the time it came ashore in a sparsely populated part of Baja California on 20 August, but its moisture brought historic rain to the southwestern United States. Death Valley set an all-time daily rainfall record of 2.20 inches, more than it averages in a year, and Los Angeles and San Diego broke daily records. Hilary caused three direct deaths, two in Mexico and one in California, and NOAA's National Centers for Environmental Information put damage in the United States at about 900 million US dollars (2023).

Several storms that never made landfall still mattered. Tropical Storm Pilar took an unusual east-northeastward track toward Central America before turning back out to sea, and its rains caused four direct flood deaths, three in El Salvador and one in Honduras; the firm Aon estimated losses of 45 million US dollars (2023). Calvin passed about 60 n mi south of Hawaii's Big Island as a weakening tropical storm and caused flooding but no reported damage. Dora passed far south of Hawaii and caused no direct damage, but the Hurricane Center links it indirectly to the Maui wildfires: the pressure contrast between Dora and a strong high to the north helped drive the dry, gusty winds that spread the fires, which killed 102 people in Lahaina.

A forecasting failure and two retired names

Otis exposed the limits of intensity forecasting. Neither forecasters nor the model guidance anticipated its rapid intensification, and some global models had suggested it might dissipate. One of the Hurricane Center's Otis forecasts produced the largest 48-hour intensity error in the basin since Patricia. A hurricane warning for Acapulco went out only about 21 hours before tropical-storm-force winds arrived, and a single Air Force Reserve reconnaissance flight caught the storm in the middle of its intensification.

In March 2024 the World Meteorological Organization retired the names Dora and Otis, replacing them with Debora and Otilio. It was the first time more than one name had been retired from the list used east of 140°W in a single season.