Last updated: April 17, 2025
The climate of Manu'a, American Samoa, is classified under the Köppen-Geiger system as Af, signifying a tropical rainforest environment characterized by consistently high temperatures and humidity. Throughout the year, temperatures exhibit minimal variation, ranging from a minimum of 24°C (76°F) in June to a maximum of 30°C (86°F) in February, with an average temperature hovering around 27°C (81°F). This stable thermal regime, coupled with abundant precipitation typical of Af climates, creates a lush and vibrant ecosystem that supports diverse flora and fauna, further influencing the cultural and environmental dynamics of the region.
Temperature patterns in Manu'a, American Samoa, exhibit a consistent tropical profile throughout the year, with average monthly temperatures maintaining a steady 27°C (81°F). The minimum temperatures generally fluctuate between 24°C (76°F) and 25°C (77°F), peaking in the cool months of June and November, while maximum temperatures range from 28°C (83°F) to 30°C (86°F), with February recording the highest temperatures. Seasonal trends reveal a slight dip in maximum temperatures during the mid-year months of July, August, and September, where values remain in the lower range, coupled with stable averages. This predictably warm climate contributes to the region's lush biodiversity, offering a habitat that thrives in these consistently high temperatures.
The climate of Ta'u, Faleasao, and Ofu is characterized by consistent temperatures, with a minimum of 24°C (76°F) recorded in June and a maximum of 30°C (86°F) reached in February for all three locations. For more detailed information, you can explore the monthly temperatures in Ta`u here, in Faleasao here, and in Ofu here.
Precipitation in Manu'a, American Samoa, exhibits significant variation throughout the year, with the wettest months typically occurring from November to February. February stands out as the peak month, recording an impressive 463 mm (18.2 in) of rainfall over 25 days, while January follows closely with 283 mm (11.1 in) over 24 days. These months are essential for replenishing the island’s lush vegetation and sustaining its unique biodiversity. The transition from wet to dry seasons can be observed, with pronounced decreases in rainfall starting in March and continuing through the mid-year months.
As the dry season approaches, precipitation steadily declines, reaching the lowest point in August with just 112 mm (4.4 in) of rain over 18 days. The pattern of rainfall illustrates a seasonal rhythm inherent in the tropical climate, where the months of June, July, and August see significant drops, with averages as low as 134 mm (5.3 in) or less. Following August, a resurgence in rainfall occurs starting in September, gradually increasing toward the end of the year, indicating a cyclical return to the wetter conditions characteristic of Manu'a’s climate. This interplay of wet and dry periods profoundly influences local agriculture and ecosystem health.
The humidity in Manu'a, American Samoa, presents a notable pattern throughout the year, consistently hovering between 79% and 84%. January to April welcomes a slightly lower humidity range of 79% to 80%, creating a more comfortable atmosphere. However, as May rolls in, the humidity steadily rises, peaking during the summer months of August and September at an impressive 83% and 84%, respectively. This trend reflects the region's tropical climate, where the air feels increasingly moist as the year progresses, before slightly tapering off in the final months. Overall, residents and visitors alike can expect a humid environment, particularly in the latter half of the year, emphasizing the lush, vibrant nature that characterizes this beautiful island locale.
In Manu'a, American Samoa, sunshine duration displays a clear seasonal trend, reflecting the island's tropical climate. The year begins with relatively lower sunshine hours in January and February, recording 232 hours and 229 hours respectively. However, as the seasons progress into spring and summer, there is a noticeable increase, peaking in March with an impressive 310 hours of sunshine. This upward trend continues through the summer months, with October and September also showcasing robust sunshine durations at 303 hours and 301 hours, respectively, indicating that these periods are marked by clear skies and abundant sunlight.
Conversely, the latter part of the year does witness a slight decline in sunshine hours, yet the totals remain substantial. November and December continue to provide generous sunshine, with 299 hours and 290 hours, demonstrating that even in the rainy season, sunlight is a prominent feature. Overall, the sunshine data underscores a transition from the cooler, cloudier winter months to the brighter, sun-kissed summer periods, creating an inviting environment that enhances both the landscape and the quality of life in Manu'a, making it a desirable location for both residents and visitors alike.
The UV Index in Manu'a, American Samoa, reveals consistently high levels of ultraviolet radiation throughout the year, particularly in the early months. Both January and February report a UV Index of 16, classified as extreme, indicating that unprotected skin can burn within just 10 minutes of exposure. As the year progresses into March, the index drops slightly to 15, yet remains in the extreme category. April and May also display high values, with indices of 13 and 11 respectively. This persistent level of intensity underscores the need for rigorous sun protection during these months, particularly for outdoor activities.
Entering the mid-year, the UV Index slightly decreases, with June and July recording a value of 9, categorized as very high, thus extending the unprotected burn time to 15 minutes. However, from August to November, the UV Index climbs again, peaking at 15 in several months and maintaining the extreme category, reminding residents and visitors alike of the perennial importance of sun safety. Overall, individuals in Manu'a should remain vigilant about UV exposure year-round, employing protective measures to mitigate the risks associated with high levels of ultraviolet radiation.
UV Risk Categories
Daylight duration in Manu'a, American Samoa, exhibits a fascinating consistency across much of the year, with 12 hours of daylight prevalent from January through March. This steady provision of sunlight fosters a vibrant environment conducive to both agriculture and outdoor activities. However, a subtle shift occurs in the spring and summer months, as daylight hours decline slightly to 11 hours from April through August, marking a period of reduced natural light exposure.
As daylight duration gradually increases again, September marks a return to 12 hours of sunlight, extending into October, November, and December. This cyclical pattern, characterized by balanced daylight hours year-round, emphasizes the region's equatorial location, where extensive daylight can frequently be expected. The relative stability in daylight duration facilitates the island's unique ecosystems and reinforces the cultural rhythms of its inhabitants, who harmonize their activities with the natural light cycle.
Faleasao, American Samoa enjoys a tropical climate with consistent temperatures throughout the year, averaging around 27°C (81°F) and rarely fluctuating beyond 29°C (85°F). The wettest months are February and November, receiving up to 457 mm (18.0 in) and 263 mm (10.3 in) of rainfall, respectively, while the driest months are June and September, with around 138 mm (5.4 in) and 93 mm (3.7 in) of precipitation. Sunshine is abundant, particularly in March and October, with over 300 hours of sun per month on average. The combination of warm temperatures and varying rainfall creates a lush environment characteristic of the region. For more detailed information, visit Faleasao climate.
Ofu, American Samoa experiences a tropical climate characterized by warm temperatures year-round, with averages consistently around 27°C (81°F). The wettest months are typically February and November, receiving over 260 mm of rainfall, while August and September are relatively drier with around 106 mm. Sunshine is abundant, especially in March and October, boasting over 300 hours of sun during those months. This combination of warmth and moisture creates a lush environment, ideal for diverse flora and fauna. For more detailed information, visit Ofu climate.
Tau, American Samoa, experiences a tropical climate characterized by warm temperatures and significant rainfall throughout the year. Average temperatures hover around 27°C (81°F), with monthly highs generally between 28°C (83°F) and 30°C (86°F). January and February are the wettest months, receiving approximately 285 mm and 457 mm of precipitation, respectively, while August tends to be the driest with just 111 mm. Despite the high rainfall, the region enjoys ample sunshine, particularly in March and October, which see over 300 hours of sunlight. For more details, visit the [Tau climate](/climate/american-samoa/manu-a/ta-u.html) page.
In conclusion, the climate of Manu'a, American Samoa, is characterized by consistently high temperatures, abundant precipitation, and a stable daylight duration, fostering a lush and vibrant natural environment. The combination of extreme UV Index levels and varied sunshine hours underscores the importance of sun safety and protection, particularly during the wetter months. As daylight duration remains fairly consistent throughout the year, residents and visitors alike can plan their activities to maximize enjoyment of the outdoors while being mindful of the region's unique climatic conditions. Overall, Manu'a's climate not only shapes its stunning landscapes but also profoundly influences the lifestyle and culture of its inhabitants.