September Weather in Pago Pago American Samoa
Daily high temperatures are around 85°F, rarely falling below 81°F or exceeding 88°F.
Daily low temperatures are around 78°F, rarely falling below 74°F or exceeding 81°F.
For reference, on February 26, the hottest day of the year, temperatures in Pago Pago typically range from 78°F to 88°F, while on August 9, the coldest day of the year, they range from 77°F to 84°F.
Average High and Low Temperature in September in Pago Pago
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. The horizontal axis is the day, 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 September in Pago Pago
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
The month of September in Pago Pago experiences rapidly increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 39% to 55%.
The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 61% of the time.
For reference, on January 7, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 88%, while on August 25, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 61%.
Cloud Cover Categories in September in Pago Pago
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. In Pago Pago, the chance of a wet day over the course of September is very rapidly increasing, starting the month at 23% and ending it at 37%.
For reference, the year's highest daily chance of a wet day is 63% on January 16, and its lowest chance is 17% on July 29.
Probability of Precipitation in September in Pago Pago
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during September in Pago Pago is rapidly increasing, starting the month at 2.0 inches, when it rarely exceeds 4.4 inches or falls below 0.1 inches, and ending the month at 3.7 inches, when it rarely exceeds 7.2 inches or falls below 0.9 inches.
Average Monthly Rainfall in September in Pago Pago
Over the course of September in Pago Pago, the length of the day is gradually increasing. From the start to the end of the month, the length of the day increases by 23 minutes, implying an average daily increase of 47 seconds, and weekly increase of 5 minutes, 28 seconds.
The shortest day of the month is September 1, with 11 hours, 50 minutes of daylight and the longest day is September 30, with 12 hours, 13 minutes of daylight.
Hours of Daylight and Twilight in September in Pago Pago
The latest sunrise of the month in Pago Pago is 6:27 AM on September 1 and the earliest sunrise is 21 minutes earlier at 6:06 AM on September 30.
The earliest sunset is 6:17 PM on September 1 and the latest sunset is 1 minute, 18 seconds later at 6:19 PM on September 30.
Daylight saving time is not observed in Pago Pago during 2023.
For reference, on December 22, the longest day of the year, the Sun rises at 5:52 AM and sets 12 hours, 59 minutes later, at 6:50 PM, while on June 21, the shortest day of the year, it rises at 6:46 AM and sets 11 hours, 17 minutes later, at 6:03 PM.
Sunrise & Sunset with Twilight in September in Pago Pago
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 September in Pago Pago
The figure below presents a compact representation of key lunar data for September 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. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.
Moon Rise, Set & Phases in September in Pago Pago
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 chance that a given day will be muggy in Pago Pago is essentially constant during September, remaining around 99% throughout.
For reference, on January 1, the muggiest day of the year, there are muggy conditions 100% of the time, while on July 23, the least muggy day of the year, there are muggy conditions 98% of the time.
Humidity Comfort Levels in September in Pago Pago
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 Pago Pago is gradually decreasing during September, decreasing from 14.8 miles per hour to 14.0 miles per hour over the course of the month.
For reference, on July 29, the windiest day of the year, the daily average wind speed is 15.0 miles per hour, while on March 9, the calmest day of the year, the daily average wind speed is 10.4 miles per hour.
Average Wind Speed in September in Pago Pago
The hourly average wind direction in Pago Pago throughout September is predominantly from the east, with a peak proportion of 87% on September 21.
Wind Direction in September in Pago Pago
Pago Pago 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 surface water temperature in Pago Pago is essentially constant during September, remaining around 82°F throughout.
Average Water Temperature in September in Pago Pago
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 Pago Pago 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 September in Pago Pago
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.
The average accumulated growing degree days in Pago Pago are rapidly increasing during September, increasing by 893°F, from 1,874°F to 2,767°F, over the course of the month.
Growing Degree Days in September in Pago Pago
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 in Pago Pago is essentially constant during September, remaining within 0.2 kWh of 5.8 kWh throughout.
The highest average daily incident shortwave solar energy during September is 6.0 kWh on September 21.
Average Daily Incident Shortwave Solar Energy in September in Pago Pago
For the purposes of this report, the geographical coordinates of Pago Pago are -14.278 deg latitude, -170.702 deg longitude, and 472 ft elevation.
The topography within 2 miles of Pago Pago contains very significant variations in elevation, with a maximum elevation change of 1,929 feet and an average elevation above sea level of 453 feet. Within 10 miles also contains very significant variations in elevation (1,932 feet). Within 50 miles also contains very significant variations in elevation (1,932 feet).
The area within 2 miles of Pago Pago is covered by trees (57%) and water (39%), within 10 miles by water (90%), and within 50 miles by water (100%).
This report illustrates the typical weather in Pago Pago, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Pago Pago.
For each station, the records are corrected for the elevation difference between that station and Pago Pago according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Pago Pago is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Pago Pago and a given station.
The stations contributing to this reconstruction are:
To get a sense of how much these sources agree with each other, you can view a comparison of Pago Pago and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for airports and weather stations are provided by AskGeo.com .
Maps are © OpenStreetMap contributors.
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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