September Weather in Anchorage Alaska, United States
Daily high temperatures decrease by 11°F, from 62°F to 51°F, rarely falling below 44°F or exceeding 67°F.
Daily low temperatures decrease by 10°F, from 49°F to 39°F, rarely falling below 30°F or exceeding 53°F.
For reference, on July 20, the hottest day of the year, temperatures in Anchorage typically range from 55°F to 68°F, while on January 17, the coldest day of the year, they range from 13°F to 23°F.
Average High and Low Temperature in September in Anchorage
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 Anchorage
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 Anchorage experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 59% throughout the month. The highest chance of overcast or mostly cloudy conditions is 60% on September 19.
The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 42% of the time.
For reference, on December 18, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 63%, while on March 16, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 48%.
Cloud Cover Categories in September in Anchorage
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 Anchorage, the chance of a wet day over the course of September is gradually increasing, starting the month at 36% and ending it at 38%.
For reference, the year's highest daily chance of a wet day is 39% on September 27, and its lowest chance is 13% on March 28.
Probability of Precipitation in September in Anchorage
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 Anchorage is gradually decreasing, starting the month at 3.1 inches, when it rarely exceeds 5.0 inches or falls below 1.5 inches, and ending the month at 2.7 inches, when it rarely exceeds 4.9 inches or falls below 1.3 inches.
The highest average 31-day accumulation is 3.1 inches on September 5.
Average Monthly Rainfall in September in Anchorage
Over the course of September in Anchorage, 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 2 hours, 44 minutes, implying an average daily decrease of 5 minutes, 40 seconds, and weekly decrease of 39 minutes, 39 seconds.
The shortest day of the month is September 30, with 11 hours, 29 minutes of daylight and the longest day is September 1, with 14 hours, 13 minutes of daylight.
Hours of Daylight and Twilight in September in Anchorage
The earliest sunrise of the month in Anchorage is 6:51 AM on September 1 and the latest sunrise is 1 hour, 12 minutes later at 8:04 AM on September 30.
The latest sunset is 9:05 PM on September 1 and the earliest sunset is 1 hour, 32 minutes earlier at 7:33 PM on September 30.
Daylight saving time is observed in Anchorage during 2022, 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 4:20 AM and sets 19 hours, 22 minutes later, at 11:42 PM, while on December 21, the shortest day of the year, it rises at 10:14 AM and sets 5 hours, 27 minutes later, at 3:41 PM.
Sunrise & Sunset with Twilight in September in Anchorage
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 in Anchorage
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 Anchorage is essentially constant during September, remaining around 0% throughout.
For reference, on June 19, 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 in Anchorage
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 Anchorage is gradually increasing during September, increasing from 4.9 miles per hour to 5.7 miles per hour over the course of the month.
For reference, on January 8, the windiest day of the year, the daily average wind speed is 6.6 miles per hour, while on July 6, the calmest day of the year, the daily average wind speed is 4.2 miles per hour.
The highest daily average wind speed during September is 5.7 miles per hour on September 28.
Average Wind Speed in September in Anchorage
The wind direction in Anchorage during September is predominantly out of the south from September 1 to September 11 and the east from September 11 to September 30.
Wind Direction in September in Anchorage
Anchorage 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 Anchorage is decreasing during September, falling by 5°F, from 54°F to 49°F, over the course of the month.
Average Water Temperature in September in Anchorage
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 in Anchorage typically lasts for 5.1 months (156 days), from around April 25 to around September 29, rarely starting before April 10 or after May 12, and rarely ending before September 11 or after October 15.
During September in Anchorage, the chance that a given day is within the growing season is very rapidly decreasing falling from 98% to 47% over the course of the month.
Time Spent in Various Temperature Bands and the Growing Season in September in Anchorage
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 Anchorage are gradually increasing during September, increasing by 74°F, from 896°F to 970°F, over the course of the month.
Growing Degree Days in September in Anchorage
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 Anchorage is decreasing during September, falling by 1.4 kWh, from 3.3 kWh to 1.9 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in September in Anchorage
For the purposes of this report, the geographical coordinates of Anchorage are 61.218 deg latitude, -149.900 deg longitude, and 98 ft elevation.
The topography within 2 miles of Anchorage contains only modest variations in elevation, with a maximum elevation change of 177 feet and an average elevation above sea level of 48 feet. Within 10 miles contains only modest variations in elevation (3,212 feet). Within 50 miles contains large variations in elevation (7,936 feet).
The area within 2 miles of Anchorage is covered by artificial surfaces (79%) and sparse vegetation (14%), within 10 miles by water (29%) and trees (22%), and within 50 miles by trees (32%) and shrubs (21%).
This report illustrates the typical weather in Anchorage, 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 Anchorage.
For each station, the records are corrected for the elevation difference between that station and Anchorage 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 Anchorage is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Anchorage 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 Anchorage 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 © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.
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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