American Samoa experiences a tropical climate (Köppen classification Aw) with hot, wet summers and warm, dry winters. The climate is characteristically hot, humid, and wet, with sunny days throughout the year. American Samoa is an unincorporated territory of the United States that lies to the southeast of Samoa in the South Pacific Ocean. Low latitudes and engulfment by the Pacific Ocean chiefly influence the climate of the islands.
American Samoa, nicknamed Motu o Fiafiaga or the Islands of Paradise, consists of five rocky, volcanic islands and two coral atolls. Lata Mountain has the highest elevation at 970 meters above sea level. The islands are home to the highest sea cliffs in the world at 910 meters. Remarkable coastal reef ecologies and rainforests give the islands the highest marine biodiversity in the United States. The volcanic islands of Tutuila, Ofu, Olosega, and Ta'u receive between 120" (3048mm) along the coasts to 200" (5080mm) in the hilly regions and are wetter than the small islands. Aunu'u, along with Swains and Rose atolls, receives up to 100" (2540mm) of rainfall.
American Samoa has two different seasons, a prominently wet one from October to May and a dry one from June to September. The usual temperature range over the year is between 70°F (21.1°C) to 90°F (32.2°C), with mostly humid days amid cloud cover. Summer average temperatures are above 80°F (26.7°C) with rare extremes. Winter is the coldest time of the year from June to September in the southern hemisphere. However, temperatures rarely vary by more than 15°F (-9.4°C) throughout the year. The dry season also sees rainfall activity, but it is significantly lesser compared to the wet season. Trade winds from the southeast bring clouds and rain throughout the year. The annual rainfall in American Samoa ranges between an abundant 71" (1803.4mm) to 200" (5080mm), mainly due to the orographic effect. The annual mean rainfall over the Pago Pago area is 120" (3048mm), with the surrounding mountains receiving up to 200" (5080mm). The year-round tropical climate has moderate temperatures but significant humidity due to trade winds and cloud cover. The proximity to the equator, at just 14°southern latitude, gives equal hours of days and nights and minimum temperature variations. The average annual sunshine lasts for 2400 hours, along with an average humidity that remains above 80%. Snowfall is absent in American Samoa.
Malaeloa / Aitulagi recorded the highest temperature in American Samoa of 99°F (37.2°C) on April 27, 1972, and also the coldest temperature of 53°F (11.7°C) on March 28, 1962.
The best time to visit American Samoa
The best time to visit American Samoa is in the short and relatively dry winter season from June to September. The coldest period of the year sees a drastic rise in tourist population with a vast coastline, abundant public beaches, and a diverse landscape in the backdrop of mountains. The days are sunny and bright even at the peak of the winter, while the nights are comfortable. The season is perfect for romantic getaways, water adventures, and family vacations. However, do not expect entirely dry days as rain is omnipresent in American Samoa.
The worst time to visit American Samoa
The worst time to visit American Samoa is from December to March when the rainfall is the heaviest in the year. Thunderstorms are frequent, and the rainfall is intense, although for short periods. The long summer season is at its peak, and temperatures climb to 90°F (32.2°C) along with a stifling rise in humidity. Tropical cyclones of the South Pacific are frequent between late December and March but occasionally occur in November and stretch up to May. A good reason for budget travelers to consider the slack season is the significant reduction in flight and accommodation costs.
American Samoa is prone to thunderstorms, tropical cyclones, hurricanes, earthquakes, and tsunamis. It lies in the Pacific Ring of Fire and vulnerable to earthquakes, such as the one that occurred on September 29, 2009. The 8.1 magnitude earthquake resulted in tsunamis that killed more than 170 people in the islands. Tropical cyclones frequently occur between December and April. Thunderstorms are frequent in the long summer and drive big waves towards the islands in conjunction with high-speed winds. Heavy rainfall is a significant threat during the peak wet season and even the rest of the year.
Weather in January
January brings hot temperatures in American Samoa with plenty of rain. The days receive ample sunshine during the summer, even though it rains almost daily. Afternoons are particularly prone to thunderstorms with brief, intense periods of rain followed by bright sunshine. The average temperatures are in the 77°F (25°C) to 88°F (31.1°C) range, but tend to be slightly lower at high elevations on the volcanic islands. Pago Pago, the capital, receives an average of 14.4" (365.8mm) of precipitation in the space of 24 rainy days. Sea temperatures remain fairly steady above the 84°F (28.9°C) mark and the waters are warm enough for swimming. However, tropical cyclones pose a threat during the southern summer, and it is advisable to keep an eye on the weather forecast. Tourist numbers remain impressive during the New Year. American Samoa is one of the favorite destinations to escape from the brutally cold northern hemisphere winters in January.
Weather in February
February has hot and humid conditions in American Samoa as the average temperatures register in the steady 77°F (25°C) to 88°F (31.1°C) range. Heatwaves are generally uncommon, but the humidity keeps the conditions oppressive. Swimming or surfing in mild ocean waters is the best way to counter the heat. Mornings and evenings provide comfortable weather to venture out in search of the diverse marine life on the islands or to explore the moderately high hills and mountains. The average sea temperatures of 84°F (28.9°C) are perfect for sailing, snorkeling, and exploring the underwater sea life that is difficult to find elsewhere in the North American winter. Volcanic fog is a queer phenomenon at higher elevations. The rainforests are home to fruit bats, lorikeets, shrikebills, ground-doves, and many other birds and animals. February nights are comfortably warm in the hot summer of American Samoa.
Weather in March
March is the warmest month in American Samoa with day temperatures climbing up to 90°F (32.2°C) and an average of 24 rainy days. The average high temperatures are in the 84°F (28.9°C) to 88°F (31.1°C), but the humidity above 80% makes the conditions uncomfortable. Sweatshirts and shorts are the usual order of the day, while the nights are slightly cooler. The sunshine is bright and lasts for at least 8 hours during the 12-hour days. Carry an umbrella or a light rain jacket while exploring the National Park spread across the islands as rain is imminent. Dense jungles, coconut and palm trees, and sighting of occasional mountain peaks through the trees make for scenic photography in the bright sunshine. Tropical cyclones are frequent during the month, and it is prudent to keep the weather in contention while planning for outdoor adventures. March is an excellent opportunity for budget travelers to visit American Samoa with discounted flights and accommodations.
Weather in April
April is prone to cyclonic conditions in American Samoa with significant periods of rain in the long summer season. Cloudy skies are regular, and afternoons are particularly susceptible to rain. The day temperatures inch up to 90°F (32.2°C), but the surrounding ocean regulates the heat to a large extent. The precipitation averages 11" (279.4mm) in the month with 22 wet days. Sheltered coasts generally receive less rainfall than the open ones where the trade winds run amok. Wind speeds are high, and it is advisable to heed to weather warnings as the usually calm ocean water may run into a rough zone. The tourist population is at its lowest, and there are plenty of deals for budget travelers. Intense rainfall can lay a spoilsport during planned vacations and keep visitors confined to hotels and nearby areas many a time. It is a good idea to avoid American Samoa in April with better weather in the ensuing months.
Weather in May
May is the last month of the hot and long summer in American Samoa as well as the wet season. The average temperatures in Pago Pago are in the 77°F (25°C) to 86°F (30°C) and fare in a similar range in the rest of the islands. The precipitation begins to scale down but registers at least 10" (254mm) in the month. Cloudy skies are standard along with sunny days as the conditions transition gradually to the drier cycle of the year. Ocean temperatures are moderate, and there is a supply of fresh air, especially in the mornings and evenings. Light summer clothing is the order of the day in May while exploring the mountains, trails, or beaches. Use reasonable sun protection in open areas such as unsheltered beaches as the equatorial sun rays are intense. May provides more open spots on the beaches as the tourist season is yet to begin in American Samoa.
Weather in June
June is the beginning of the dry season in American Samoa with cooler temperatures and a decrease in rainfall. The average high temperatures are in the 77°F (25°C) to 88°F (31.1°C) range, with slightly cooler nights that occasionally drop below 70°F (21.1°C). The coral reefs have turquoise waters with the average sea temperature at 82°F (27.8°C) - perfect for snorkeling and scuba diving. The sunrays are brilliant, and the cloud cover lasts for short periods. Humidity and heat are at the least of the year, and the beaches and forests yearn for visitors. The end of the cyclone season is the right time to charter a boat or take a cruise in the calm waters and explore the islands by sea. The tourist population is on the rise, as are hotel and flight rates. The conditions are perfect for visiting American Samoa in June as the precipitation is at the lowest of the year.
Weather in July
July is the coldest month in the dry season of American Samoa, with the average temperatures in the 75°F (23.9°C) to 82°F (27.8°C) range. The precipitation is low compared to the wet season, yet rain marks its attendance for 19 days in the month. Wind speeds are usually below 15mph (24.1km/h), and the ocean waters are calm. Gentle breezes make the atmosphere enjoyable, especially near the sea coast. Trade winds that originate from subtropical high-pressure areas in the Southern Hemisphere dominate the climatic conditions. Ofu Beach sees a large number of tourists, and the sunrise and sunset are a treat to watch in the company of turquoise waters. The temperatures are suitable for light summer clothing in the day, while the comfortable nights rarely need additional layers. Cyclones and thunderstorms rarely occur to give an uninterrupted joy of adventure. July is the peak of the tourist season in American Samoa due to the best conditions of the year.
Weather in August
August is a month with cozy weather in American Samoa, with the average temperatures between 76°F (24.4°C) to 84°F (28.9°C). The conditions are among the best of the year for game fishing with ample tuna, marlin, skipjack, and fully-equipped fishing boats for hire. The crystal-clear waters in the coral reefs give one of the most amazing views of underwater marine life, with a variety of fishes just near the coast. Visitors can spot green turtles near the coast, whose numbers peak in August. Maintain distance from turtle nesting sites, especially during the nights when they are active. The sunshine is bright, and the call of the rocky cliffs, volcanic islands, and dense rainforests is irresistible. Loose-fitting summer clothing is suitable during the day, but wear stout shoes while roaming through the rainforests. August is heavy on the wallet with the tourist season at its peak in American Samoa.
Weather in September
September is a relatively dry month in American Samoa with bright sunshine amid comfortable temperatures. Night temperatures drop to a cozy 70°F (21.1°C) with a decrease in humidity. The average high temperatures rarely cross 84°F (28.9°C) and drop by a few degrees on the mountain peaks. The coastline of white, sandy beaches is further exposed during low tide and draws a large number of tourists. The ocean water temperatures are at the lowest of the year, with the average registering at 81°F (27.2°C). September is a good time to climb Mount Alava with a break in the rain that offers an uninterrupted view of the archipelago of the surrounding islands. Winds are rarely troublesome with moderate speeds that are mostly of the gentle breeze type. Sunny days greet the tourists, whether on the beaches or the mountains and forests. September is a good time to visit American Samoa with comfortable weather that gradually transitions to hot and humid with the end of the dry season.
Weather in October
October is the beginning of the wet season in American Samoa that sees a rise in dampness, humidity, and temperatures. The precipitation is above 10" (254mm) in Pago Pago and averages between 9" (228.6mm) to 10" (254mm) in the rest of the islands. The average temperatures are between 77°F (25°C) to 86°F (30°C), and humidity remains above 80%. Afternoon thunderstorms with lightning are frequent in October, along with intense spells of rain. Tidal patterns see a change in the ocean waters and create occasional big waves. Surfers love the waters and are ready for adventure, while sailing boats float dreamily in the clear waters. The sunshine lasts at least 8 hours daily, even though the cloud cover is significant. An umbrella or a rain jacket is mandatory for outdoor visits, especially in the rainforests, where the canopy of trees can keep conditions wet. October is a reasonable time to visit American Samoa for people who can withstand wet weather.
Weather in November
November sees heavy rainfall in American Samoa with the advance of the wet season. Clouds regularly cover the skies, and the volcanic islands are susceptible to fog. Sunlight is never short in American Samoa, even in the wet season. The average temperatures are in the 78°F (25.6°C) to 86°F (30°C) range as the long and hot summer season takes its toll. Day temperatures are still comfortable, and nights tend to be on the cozy side. Wind speeds are the lowest of the year in November and classify as a light breeze. Rain protection gear is necessary while exploring outdoors. The tropical cyclone season begins by late November with substantial rainfall, thunder, and lightning, which makes it prudent to keep an eye on the weather forecast. Tourist numbers drop by November in American Samoa, so it is an excellent opportunity for people looking to travel on a budget while the conditions are bearable.
Weather in December
December begins a prominently wet period in American Samoa as the territory receives the highest monthly rainfall of the year. The islands average 14.6" (370.8mm) of precipitation, and the conditions remain wet and humid. The average high temperatures register above 88°F (31.1°C), while the average low temperatures are only a shade lower at 77°F (25°C). Cloudy skies are the rule rather than the exception during the afternoons. The heat is oppressive during the day due to the high humidity, although afternoon thundershowers provide welcome relief. Tropical cyclones frequently invade the coast and surge inland during the storm season. Tourist numbers are less compared to the winter, and there are plenty of spaces on the beaches. Watch out for heavy rain, which is a regular feature in the afternoons. Loose-fitting tropical clothing along with a light sweatshirt, sun hat, and an umbrella is perfect for December in American Samoa.