Climate and monthly weather forecast
American Samoa, USA

Flag of American Samoa, USA
Flag of American Samoa, USA

The climate of American Samoa

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" (1803mm) 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.

Weather hazards

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. Weather 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. Weather in February »

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. Weather in March »

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" (279mm) in the month with 22 wet days. Weather in April »

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 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. Weather in May »

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. Weather in June »

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. Weather in July »

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. Weather in August »

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. Weather in September »

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 and averages between 9" (229mm) 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%. Weather in October »

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. Weather in November »

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" (371mm) 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). Weather in December »

American Samoa, USA - most visited locations


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