Climate Impacts and Outlook

Highlights for Hawaii and the U.S. Affiliated Pacific Islands

Funnel cloud observed on 1/28/25 south of Pago Pago International Airport, Tutuila Island, American Samoa. Source: National Weather Service, Pago Pago.

Severe weather associated with the South Pacific Convergence Zone led to significant landslide activity on Taʻū Island, Manuʻa Islands, American Samoa in late February 2025. Source: Manu’atele Community Worldwide, FB.

Late-January storm event rainfall totals for Oahu, Maui, and Big Island, which brought flash flooding, power outages, and school closures (12/8/24).
Source: National Weather Service, Honolulu.

Facilities and Infrastructure– In the Manuʻa Islands of American Samoa, heavy rainfall and saturated soils triggered landslides that blocked roadways between the villages of Fitiuta, Taʻū, and Faleāsao in late February. In the Hawaiian Islands, a strong low-pressure system brought heavy rainfall and flash flooding across areas of the island chain, with the worst flooding observed in the Kuliʻouʻou and Hawaiʻi Kai areas on Oahu and in southwest Maui in Kīhei, where areas of South Kīhei Road were closed due to flooding which impacted businesses and residences. On the Big Island, flooding led to school closures at 6 public school in South Kona. In addition, Hawaiian Electric reported power outages to customers on Hawaii, Maui, and Oahu counties where gale-force winds downed trees and debris onto power lines (1/30-31/25).

Heat – In the western Pacific, anomalously warm air temperatures were observed during the DJF period in areas of the Marianas, FSM, and RMI (below). In the Commonwealth of the Northern Mariana Island, Saipan International Airport observed it warmest DJF period on record with a 3-month mean maximum temperature of 88.9ºF as well as its highest 3-month mean minimum temperature (78.5ºF) on record. In FSM, Pohnpei logged its warmest DJF mean average temperature (83.2ºF) and its warmest mean minimum temperature (78.8ºF) on record.

2-meter surface air temperature rankings for the Dec 2024-Jan 2025 period for the Pacific Ocean region.
Source: ERA5 Reanalysis, B. Brettschneider, National Weather Service.

Water Resources – IIn Majuro (RMI), reservoir storage reached 85% of total capacity (36,000,000 gallons) on 2/25/25. Across the Hawaiian Islands, 7-day average streamflows (3/4/25) were below normal at numerous USGS gauging stations, including along Hawaii’s longest river, Wailuku River (9th percentile), at Piihonua, Hawaii.

Seasonal sea surface temperature anomaly map for 12/1/24 to 3/1/25 (left) and 3-month seasonal precipitation departures from normal for the December 2024–February 2025 period for the central and western tropical Pacific Ocean with warmer colors representing drier-than-normal conditions and cooler colors wetter-than-normal conditions (right).
Source: NOAA Physical Sciences Laboratory (left); ERA5 Reanalysis, B. Brettschneider, National Weather Service (right).

By the end of the DJF period, SSTs were near to below normal across the central and east-central tropical Pacific Ocean, while above-normal SSTs were present in a shallow layer (upper 50 meters) in the eastern tropical Pacific Ocean near South America. According to the NOAA CPC update (3/10/25), Niño region SST departures were as follows: Niño 3.4 at 0.0ºC, Niño 3 at 0.5ºC, Niño 1+2 at 1.6ºC, and Niño 4 at -0.3ºC.

Below-normal sea levels (~-5 to -10 cm anomalies) were observed in proximity to the equator (from ~5ºN to ~5ºS) during the DJF period in an area extending from the west-central Pacific Ocean through the east-central Pacific Ocean. In contrast, above-normal sea levels were observed in the Hawaiian Islands as well as across much of the western tropical Pacific, including in the Mariana Islands and areas of western FSM (~+5 to +10 cm anomalies), according to data from the University of Hawaii Sea Level Center.

During the DJF period, drought-free conditions prevailed across much of the USAPI until late January-February when drought conditions emerged in the Marianas (Saipan, Rota, Guam), areas of FSM (Yap, Pingelap), and in RMI (Kwajalein). For DJF precipitation totals, Airai (Palau) recorded 42.64 in. (125% of normal). In FSM, Yap observed 13.61 in. (62% of normal; 13th driest), Kapingamarangi 31.51 in. (96% of normal), Pohnpei 61.87 in. (154% of normal; 2nd wettest), Lukunor 32.96 in. (102% of normal), Kosrae 58.98 in. (110% of normal), and Chuuk 30.66 in. (103% of normal). In the Mariana Islands, Saipan observed 7.28 in. (72% of normal; 7th driest) and Guam 12.96 in. (87% of normal). In the RMI, Majuro observed 35.85 in. (126% of normal), while Kwajalein logged 9.46 in. (61% of normal; 12th driest). In Pago Pago, American Samoa, precipitation for DJF was well above normal (64.93 in., 161% of normal; 4th wettest). Moreover, the observing stations at Siufaga Ridge and Toa Ridge, located in the mountainous, higher-elevation terrain of the National Park of American Samoa, logged 52.90 in. and 39.26 in., respectively. In the Hawaiian Islands, dry conditions prevailed across most of the island chain during DJF, except for isolated areas of the Big Island, Maui, Molokai, and Oahu, which received significant rainfall and associated flash flooding during late-January, including in Honolulu, where a daily rainfall record (3.57 in.) was broken on 1/30/25. For the DJF period, Lihue observed 4.45 in. (40% of normal; 6th driest), Honolulu 6.11 in. (102% of normal), Molokai 3.72 in. (43% of normal; 6th driest), Kahului 5.08 in. (70% of normal), Kailua-Kona 4.07 in. (114% of normal), and Hilo 12.70 in. (42% of normal; 8th driest).

In the South Pacific region (east of 135ºE), tropical cyclone (TC) activity has been below normal, with 4 named storms and a regional Accumulated Cyclone Energy (ACE) Index of 30 (normal 45.9) by 3/1/25, according to the Colorado State University Tropical Meteorology Project.

The NOAA Coral Reef Watch four-month coral bleaching heat stress outlook (Mar-Jun 2025) calls for a high probability (90%) of high heat stress (Alert Level 1-2) developing in areas across the western tropical Pacific Ocean, including areas around the Gilbert Islands, New Guinea, and the Solomon Islands.

Looking at the March-May 2025 precipitation forecast, normal rainfall amounts are favored for eastern FSM, American Samoa, and the Hawaiian Islands. Elsewhere, above-average precipitation is forecasted for areas of central and western FSM, Palau, and areas of the Mariana Islands, while below-normal rainfall is favored in RMI.