Average Weather in September in Fairbanks Alaska, United States
In Fairbanks, the month of September is characterized by very rapidly falling daily high temperatures, with daily highs decreasing by 15°F, from 62°F to 46°F over the course of the month, and rarely exceeding 70°F or dropping below 36°F.
Daily low temperatures decrease by 12°F, from 43°F to 31°F, rarely falling below 22°F or exceeding 50°F.
For reference, on July 3, the hottest day of the year, temperatures in Fairbanks typically range from 54°F to 73°F, while on January 18, the coldest day of the year, they range from -13°F to 2°F.
Average High and Low Temperature in September
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
The month of September in Fairbanks experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 63% throughout the month. The highest chance of overcast or mostly cloudy conditions is 65% on September 26.
The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 39% of the time.
For reference, on September 25, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 65%, while on March 15, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 46%.
Cloud Cover in September
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Fairbanks, the chance of a wet day over the course of September is decreasing, starting the month at 27% and ending it at 21%.
For reference, the year's highest daily chance of a wet day is 31% on August 6, and its lowest chance is 5% on March 18.
Over the course of September in Fairbanks, the chance of a day with only rain decreases from 26% to 16%, the chance of a day with mixed snow and rain remains an essentially constant 1% throughout, and the chance of a day with only snow increases from 0% to 3%.
Probability of Precipitation in September
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 Fairbanks is decreasing, starting the month at 1.8 inches, when it rarely exceeds 3.2 inches or falls below 0.7 inches, and ending the month at 1.0 inches, when it rarely exceeds 1.9 inches or falls below 0.3 inches.
Average Monthly Rainfall in September
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. As with rainfall, we consider the liquid-equivalent snowfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day liquid-equivalent snowfall during September in Fairbanks is essentially constant, remaining about 0.1 inches throughout, and rarely exceeding 0.4 inches or falling below -0.0 inches.
Average Monthly Liquid-Equivalent Snowfall in September
Over the course of September in Fairbanks, 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 3 hours, 13 minutes, implying an average daily decrease of 6 minutes, 39 seconds, and weekly decrease of 46 minutes, 35 seconds.
The shortest day of the month is September 30, with 11 hours, 22 minutes of daylight and the longest day is September 1, with 14 hours, 35 minutes of daylight.
Hours of Daylight and Twilight in September
The earliest sunrise of the month in Fairbanks is 6:32 AM on September 1 and the latest sunrise is 1 hour, 27 minutes later at 7:58 AM on September 30.
The latest sunset is 9:07 PM on September 1 and the earliest sunset is 1 hour, 46 minutes earlier at 7:20 PM on September 30.
Daylight saving time is observed in Fairbanks during 2017, but it neither starts nor ends during September, so the entire month is in daylight saving time.
For reference, on June 21, the longest day of the year, the Sun rises at 2:57 AM and sets 21 hours, 51 minutes later, at 12:47 AM, while on December 21, the shortest day of the year, it rises at 10:58 AM and sets 3 hours, 41 minutes later, at 2:39 PM.
Sunrise & Sunset with Twilight in September
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 Fairbanks is essentially constant during September, remaining around 0% throughout.
For reference, on July 16, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in September
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 Fairbanks is essentially constant during September, remaining within 0.1 miles per hour of 2.7 miles per hour throughout.
For reference, on January 9, the windiest day of the year, the daily average wind speed is 4.2 miles per hour, while on July 14, the calmest day of the year, the daily average wind speed is 2.5 miles per hour.
Average Wind Speed in September
Wind Direction in September
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 Fairbanks is decreasing during September, falling by 1.5 kWh, from 3.1 kWh to 1.7 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in September
For the purposes of this report, the geographical coordinates of Fairbanks are 64.838 deg latitude, -147.716 deg longitude, and 446 ft elevation.
The topography within 2 miles of Fairbanks is essentially flat, with a maximum elevation change of 23 feet and an average elevation above sea level of 444 feet. Within 10 miles is essentially flat (1,801 feet). Within 50 miles contains very significant variations in elevation (4,357 feet).
The area within 2 miles of Fairbanks is covered by artificial surfaces (66%) and sparse vegetation (26%), within 10 miles by trees (62%) and herbaceous vegetation (17%), and within 50 miles by trees (66%) and shrubs (17%).
This report illustrates the typical weather in Fairbanks year round, 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 Fairbanks.
For each station, the records are corrected for the elevation difference between that station and Fairbanks 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 Fairbanks is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Fairbanks and a given station.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , 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 aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.