Climate and Average Weather Year Round in American Samoa American Samoa
The climate in American Samoa is hot, oppressive, windy, and overcast. Over the course of the year, the temperature typically varies from 77°F to 88°F and is rarely below 74°F or above 90°F.
Based on the beach/pool score, the best time of year to visit American Samoa for hot-weather activities is from mid June to late September.
Climate in American Samoa
The temperature in American Samoa varies so little throughout the year that it is not entirely meaningful to discuss hot and cold seasons.
Average High and Low Temperature in American Samoa
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature in American Samoa
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
In American Samoa, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in American Samoa begins around May 11 and lasts for 5.1 months, ending around October 14.
The clearest month of the year in American Samoa is August, during which on average the sky is clear, mostly clear, or partly cloudy 60% of the time.
The cloudier part of the year begins around October 14 and lasts for 6.9 months, ending around May 11.
The cloudiest month of the year in American Samoa is January, during which on average the sky is overcast or mostly cloudy 87% of the time.
Cloud Cover Categories in American Samoa
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in American Samoa varies significantly throughout the year.
The wetter season lasts 7.5 months, from October 9 to May 27, with a greater than 40% chance of a given day being a wet day. The month with the most wet days in American Samoa is January, with an average of 18.9 days with at least 0.04 inches of precipitation.
The drier season lasts 4.5 months, from May 27 to October 9. The month with the fewest wet days in American Samoa is July, with an average of 6.0 days with at least 0.04 inches of precipitation.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in American Samoa is January, with an average of 18.9 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 62% on January 16.
Daily Chance of Precipitation in American Samoa
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. American Samoa experiences extreme seasonal variation in monthly rainfall.
Rain falls throughout the year in American Samoa. The month with the most rain in American Samoa is January, with an average rainfall of 10.1 inches.
The month with the least rain in American Samoa is August, with an average rainfall of 1.6 inches.
Average Monthly Rainfall in American Samoa
The length of the day in American Samoa varies over the course of the year. In 2023, the shortest day is June 21, with 11 hours, 17 minutes of daylight; the longest day is December 21, with 12 hours, 58 minutes of daylight.
Hours of Daylight and Twilight in American Samoa
The earliest sunrise is at 5:38 AM on November 21, and the latest sunrise is 1 hour, 4 minutes later at 6:43 AM on July 10. The earliest sunset is at 5:55 PM on June 1, and the latest sunset is 58 minutes later at 6:53 PM on January 21.
Daylight saving time (DST) is not observed in American Samoa during 2023.
Sunrise & Sunset with Twilight in American Samoa
The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.
Solar Elevation and Azimuth in American Samoa
The figure below presents a compact representation of key lunar data for 2023. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.
Moon Rise, Set & Phases in American Samoa
We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.
The perceived humidity level in American Samoa, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 1% of 99% throughout.
Humidity Comfort Levels in American Samoa
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.
The average hourly wind speed in American Samoa experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 5.3 months, from May 19 to October 30, with average wind speeds of more than 12.7 miles per hour. The windiest month of the year in American Samoa is July, with an average hourly wind speed of 14.8 miles per hour.
The calmer time of year lasts for 6.7 months, from October 30 to May 19. The calmest month of the year in American Samoa is March, with an average hourly wind speed of 10.5 miles per hour.
Average Wind Speed in American Samoa
The predominant average hourly wind direction in American Samoa is from the east throughout the year.
Wind Direction in American Samoa
American Samoa is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average water temperature does not vary significantly over the course of the year, remaining within 2°F of 83°F throughout.
Average Water Temperature in American Samoa
To characterize how pleasant the weather is in American Samoa throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit American Samoa for general outdoor tourist activities is from late June to mid September, with a peak score in the second week of August.
Tourism Score in American Samoa
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit American Samoa for hot-weather activities is from mid June to late September, with a peak score in the third week of August.
Beach/Pool Score in American Samoa
For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.
Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.
Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.
Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.
Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.
Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).
Temperatures in American Samoa are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.
Time Spent in Various Temperature Bands and the Growing Season in American Samoa
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.
Growing Degree Days in American Samoa
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.
The brighter period of the year lasts for 2.2 months, from August 30 to November 6, with an average daily incident shortwave energy per square meter above 5.6 kWh. The brightest month of the year in American Samoa is October, with an average of 5.9 kWh.
The darker period of the year lasts for 3.0 months, from April 14 to July 14, with an average daily incident shortwave energy per square meter below 4.6 kWh. The darkest month of the year in American Samoa is May, with an average of 4.3 kWh.
Average Daily Incident Shortwave Solar Energy in American Samoa
For the purposes of this report, the geographical coordinates of American Samoa are -14.234 deg latitude, -169.478 deg longitude, and 0 ft elevation.
The topography within 2 miles of American Samoa is essentially flat, with a maximum elevation change of 0 feet and an average elevation above sea level of 0 feet. Within 10 miles is also essentially flat (0 feet). Within 50 miles is also essentially flat (0 feet).
The area within 2 miles of American Samoa is covered by water (100%), within 10 miles by water (100%), and within 50 miles by water (100%).
This report illustrates the typical weather in American Samoa, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
The details of the data sources used for this report can be found on the Pago Pago International Airport page.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.
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