September Weather at Barter Island LRRS Airport Alaska, United States
Daily high temperatures decrease by 10°F, from 42°F to 32°F, rarely falling below 25°F or exceeding 51°F.
Daily low temperatures decrease by 9°F, from 34°F to 25°F, rarely falling below 15°F or exceeding 40°F.
For reference, on July 31, the hottest day of the year, temperatures at Barter Island LRRS Airport typically range from 39°F to 48°F, while on February 9, the coldest day of the year, they range from -18°F to -6°F.
Average High and Low Temperature in September at Barter Island LRRS Airport
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 at Barter Island LRRS Airport
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 at Barter Island LRRS Airport experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 69% throughout the month.
The clearest day of the month is September 30, with clear, mostly clear, or partly cloudy conditions 32% of the time.
For reference, on January 17, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 84%, while on June 11, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 36%.
Cloud Cover Categories in September at Barter Island LRRS Airport
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. At Barter Island LRRS Airport, the chance of a wet day over the course of September is rapidly decreasing, starting the month at 20% and ending it at 12%.
For reference, the year's highest daily chance of a wet day is 24% on August 14, and its lowest chance is 2% on March 4.
Over the course of September at Barter Island LRRS Airport, the chance of a day with only rain decreases from 16% to 5%, the chance of a day with mixed snow and rain remains an essentially constant 2% throughout, and the chance of a day with only snow increases from 1% to 6%.
Probability of Precipitation in September at Barter Island LRRS Airport
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 at Barter Island LRRS Airport is decreasing, starting the month at 1.1 inches, when it rarely exceeds 2.0 inches or falls below 0.2 inches, and ending the month at 0.3 inches, when it rarely exceeds 0.9 inches.
Average Monthly Rainfall in September at Barter Island LRRS Airport
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day snowfall during September at Barter Island LRRS Airport is increasing, starting the month at 1.5 inches, when it rarely exceeds 4.6 inches or falls below -0.0 inches, and ending the month at 3.1 inches, when it rarely exceeds 8.0 inches.
Average Monthly Snowfall in September at Barter Island LRRS Airport
Due to its extreme latitude, Barter Island LRRS Airport experiences polar day (also known as the midnight Sun) during the summer and polar night during the winter. These are periods of time in which the sun is continuously above or below the horizon for more than one day. The precise start and end dates of polar day and night vary from year to year and depend on the precise location and elevation of the observer, and the local topography.
Neither polar day nor polar night occur during the month of September.
Over the course of September at Barter Island LRRS Airport, the length of the day is very rapidly decreasing. From the start to the end of the month, the length of the day decreases by 4 hours, 14 minutes, implying an average daily decrease of 8 minutes, 45 seconds, and weekly decrease of 1 hour, 1 minute, 16 seconds.
The shortest day of the month is September 30, with 11 hours, 12 minutes of daylight and the longest day is September 1, with 15 hours, 26 minutes of daylight.
Hours of Daylight and Twilight in September at Barter Island LRRS Airport
The earliest sunrise of the month at Barter Island LRRS Airport is 5:49 AM on September 1 and the latest sunrise is 1 hour, 57 minutes later at 7:47 AM on September 30.
The latest sunset is 9:15 PM on September 1 and the earliest sunset is 2 hours, 16 minutes earlier at 6:59 PM on September 30.
Daylight saving time is observed at Barter Island LRRS Airport during 2022, but it neither starts nor ends during September, so the entire month is in daylight saving time.
Sunrise & Sunset with Twilight in September at Barter Island LRRS Airport
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 at Barter Island LRRS Airport
The figure below presents a compact representation of key lunar data for September 2022. 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 at Barter Island LRRS Airport
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 at Barter Island LRRS Airport is essentially constant during September, remaining around 0% throughout.
Humidity Comfort Levels in September at Barter Island LRRS Airport
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 at Barter Island LRRS Airport is increasing during September, increasing from 9.9 miles per hour to 11.4 miles per hour over the course of the month.
For reference, on January 13, the windiest day of the year, the daily average wind speed is 13.0 miles per hour, while on July 12, the calmest day of the year, the daily average wind speed is 8.6 miles per hour.
Average Wind Speed in September at Barter Island LRRS Airport
The hourly average wind direction at Barter Island LRRS Airport throughout September is predominantly from the east, with a peak proportion of 48% on September 30.
Wind Direction in September at Barter Island LRRS Airport
Barter Island LRRS Airport 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 at Barter Island LRRS Airport is gradually decreasing during September, falling by 3°F, from 36°F to 33°F, over the course of the month.
Average Water Temperature in September at Barter Island LRRS Airport
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).
The growing season at Barter Island LRRS Airport typically lasts for 1.4 months (44 days), from around July 5 to around August 18, rarely starting before June 12, or ending after September 16.
The month of September at Barter Island LRRS Airport is more likely than not fully outside of the growing season, with the chance that a given day is in the growing season rapidly decreasing from 27% to 2% over the course of the month.
Time Spent in Various Temperature Bands and the Growing Season in September at Barter Island LRRS Airport
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 at Barter Island LRRS Airport are essentially constant during September, remaining around 29°F throughout.
Growing Degree Days in September at Barter Island LRRS Airport
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 at Barter Island LRRS Airport is decreasing during September, falling by 1.3 kWh, from 2.4 kWh to 1.1 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in September at Barter Island LRRS Airport
For the purposes of this report, the geographical coordinates of Barter Island LRRS Airport are 70.135 deg latitude, -143.581 deg longitude, and 0 ft elevation.
The topography within 2 miles of Barter Island LRRS Airport is essentially flat, with a maximum elevation change of 62 feet and an average elevation above sea level of 7 feet. Within 10 miles is essentially flat (157 feet). Within 50 miles contains only modest variations in elevation (4,613 feet).
The area within 2 miles of Barter Island LRRS Airport is covered by water (73%) and snow and glaciers (21%), within 10 miles by water (65%) and sparse vegetation (18%), and within 50 miles by water (62%) and grassland (18%).
This report illustrates the typical weather at Barter Island LRRS Airport, 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
Barter Island LRRS Airport has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.
In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations.
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.
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