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September Weather in Sitka Alaska, United States

Daily high temperatures decrease by 6°F, from 60°F to 54°F, rarely falling below 51°F or exceeding 65°F.

Daily low temperatures decrease by 5°F, from 51°F to 47°F, rarely falling below 40°F or exceeding 55°F.

For reference, on August 10, the hottest day of the year, temperatures in Sitka typically range from 54°F to 62°F, while on February 23, the coldest day of the year, they range from 33°F to 41°F.

Average High and Low Temperature in September in Sitka

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

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 Sitka

Average Hourly Temperature in September in SitkaSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMAugOctvery coldvery coldcoldcoolcool
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 average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Ålesund, Norway (3,929 miles away) is the far-away foreign place with temperatures most similar to Sitka (view comparison).

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The month of September in Sitka experiences gradually increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 66% to 73%.

The clearest day of the month is September 1, with clear, mostly clear, or partly cloudy conditions 34% of the time.

For reference, on January 25, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 79%, while on August 11, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 38%.

Cloud Cover Categories in September in Sitka

Cloud Cover Categories in September in SitkaSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOctSep 134%Sep 134%Sep 3027%Sep 3027%Sep 1132%Sep 1132%Sep 2130%Sep 2130%clearmostly clearpartly cloudymostly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Sitka, the chance of a wet day over the course of September is very rapidly increasing, starting the month at 60% and ending it at 69%.

For reference, the year's highest daily chance of a wet day is 71% on October 30, and its lowest chance is 36% on June 20.

Probability of Precipitation in September in Sitka

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

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 Sitka is very rapidly increasing, starting the month at 8.9 inches, when it rarely exceeds 13.3 inches or falls below 4.5 inches, and ending the month at 12.1 inches, when it rarely exceeds 16.5 inches or falls below 8.2 inches.

Average Monthly Rainfall in September in Sitka

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.

Over the course of September in Sitka, 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, 19 minutes, implying an average daily decrease of 4 minutes, 47 seconds, and weekly decrease of 33 minutes, 31 seconds.

The shortest day of the month is September 30, with 11 hours, 32 minutes of daylight and the longest day is September 1, with 13 hours, 51 minutes of daylight.

Hours of Daylight and Twilight in September in Sitka

Hours of Daylight and Twilight in September in SitkaSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hrAugOctSep 2212 hr, 15 minSep 2212 hr, 15 minnightnightdaydaySep 113 hr, 51 minSep 113 hr, 51 min
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise of the month in Sitka is 6:04 AM on September 1 and the latest sunrise is 59 minutes later at 7:04 AM on September 30.

The latest sunset is 7:55 PM on September 1 and the earliest sunset is 1 hour, 19 minutes earlier at 6:36 PM on September 30.

Daylight saving time is observed in Sitka during 2024, but it neither starts nor ends during September, so the entire month is in standard time.

For reference, on June 20, the longest day of the year, the Sun rises at 4:05 AM and sets 17 hours, 54 minutes later, at 10:00 PM, while on December 21, the shortest day of the year, it rises at 8:38 AM and sets 6 hours, 42 minutes later, at 3:20 PM.

Sunrise & Sunset with Twilight in September in Sitka

Sunrise & Sunset with Twilight in September in SitkaSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930302 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMAugOct6:04 AM6:04 AMSep 17:55 PMSep 17:55 PM7:04 AM7:04 AMSep 306:36 PMSep 306:36 PM6:25 AM6:25 AMSep 117:28 PMSep 117:28 PMSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of September. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

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 Sitka

Solar Elevation and Azimuth in September in SitkaSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMAugOct0010102020304000010102020303040
northeastsouthwest
Solar elevation and azimuth over the course of September 2024. The black lines are lines of constant solar elevation (the angle of the sun above the horizon, in degrees). The background color fills indicate the azimuth (the compass bearing) of the sun. The lightly tinted areas at the boundaries of the cardinal compass points indicate the implied intermediate directions (northeast, southeast, southwest, and northwest).

The figure below presents a compact representation of key lunar data for September 2024. 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 Sitka

Moon Rise, Set & Phases in September in SitkaSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303012 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMAugOctAug 43:14 AMAug 43:14 AMAug 1910:26 AMAug 1910:26 AMSep 25:56 PMSep 25:56 PMSep 176:35 PMSep 176:35 PMOct 210:50 AMOct 210:50 AMOct 173:27 AMOct 173:27 AM4:52 AM4:52 AM9:44 PM9:44 PM8:46 PM8:46 PM5:06 AM5:06 AM5:24 AM5:24 AM8:04 PM8:04 PM7:13 PM7:13 PM7:31 AM7:31 AM7:05 AM7:05 AM6:24 PM6:24 PM5:31 PM5:31 PM8:13 AM8:13 AM
The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.
Sep 2024IlluminationMoonriseMoonsetMoonriseMeridian PassingDistance
1
1%4:01 AMNE8:00 PMWNW-12:09 PMS249,387 mi
2
0%5:24 AMENE8:04 PMWNW-12:51 PMS250,735 mi
3
1%6:43 AMENE8:07 PMW-1:30 PMS251,718 mi
4
3%8:01 AME8:09 PMW-2:08 PMS252,288 mi
5
7%9:17 AME8:12 PMWSW-2:47 PMS252,379 mi
6
13%10:35 AMESE8:16 PMWSW-3:27 PMS251,916 mi
7
20%11:56 AMESE8:21 PMSW-4:09 PMS250,825 mi
8
29%1:19 PMSE8:28 PMSW-4:54 PMS249,054 mi
9
38%2:46 PMSE8:42 PMSW-5:44 PMS246,587 mi
10
50%4:10 PMSSE9:06 PMSSW-6:38 PMS243,465 mi
11
59%5:22 PMSSE9:52 PMSSW-7:37 PMS239,806 mi
12
70%6:10 PMSSE11:05 PMSSW-8:37 PMS235,813 mi
13
80%6:38 PMSE--9:38 PMS231,774 mi
14
89%-12:39 AMSW6:53 PMSE10:37 PMS228,038 mi
15
95%-2:22 AMSW7:02 PMESE11:33 PMS224,969 mi
16
97%-4:07 AMWSW7:08 PMESE--
17
100%-5:50 AMWSW7:13 PME12:27 AMS222,890 mi
18
100%-7:31 AMW7:17 PME1:18 AMS222,025 mi
19
97%-9:13 AMWNW7:22 PMENE2:09 AMS222,455 mi
20
92%-10:57 AMWNW7:29 PMNE3:00 AMS224,106 mi
21
84%-12:42 PMNW7:40 PMNE3:53 AMS226,765 mi
22
74%-2:25 PMNW7:59 PMNE4:49 AMS230,125 mi
23
63%-3:54 PMNNW8:33 PMNNE5:47 AMS233,846 mi
24
50%-4:58 PMNNW9:32 PMNNE6:45 AMS237,609 mi
25
41%-5:35 PMNNW10:51 PMNE7:41 AMS241,155 mi
26
31%-5:54 PMNW-8:34 AMS244,305 mi
27
22%12:19 AMNE6:05 PMNW-9:23 AMS246,959 mi
28
14%1:47 AMNE6:11 PMWNW-10:08 AMS249,079 mi
29
8%3:10 AMENE6:16 PMWNW-10:50 AMS250,673 mi
30
3%4:30 AMENE6:19 PMW-11:30 AMS251,769 mi

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 Sitka is essentially constant during September, remaining around 0% throughout.

For reference, on August 28, 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 Sitka

Humidity Comfort Levels in September in SitkaSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%AugOctSep 10%Sep 10%Sep 300%Sep 300%Sep 110%Sep 110%Sep 210%Sep 210%comfortablecomfortabledrydry
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

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 Sitka is rapidly increasing during September, increasing from 9.2 miles per hour to 11.7 miles per hour over the course of the month.

For reference, on December 5, the windiest day of the year, the daily average wind speed is 13.9 miles per hour, while on July 17, the calmest day of the year, the daily average wind speed is 7.8 miles per hour.

Average Wind Speed in September in Sitka

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The hourly average wind direction in Sitka throughout September is predominantly from the south, with a peak proportion of 42% on September 27.

Wind Direction in September in Sitka

Wind Direction in September in SitkaSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%20%80%40%60%60%40%80%20%100%0%AugOctwestsoutheastnorth
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Sitka 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 Sitka is gradually decreasing during September, falling by 3°F, from 54°F to 51°F, over the course of the month.

Average Water Temperature in September in Sitka

Average Water Temperature in September in SitkaSep11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303044°F44°F46°F46°F48°F48°F50°F50°F52°F52°F54°F54°F56°F56°F58°F58°FAugOctSep 154°FSep 154°FSep 3051°FSep 3051°FSep 1153°FSep 1153°FSep 2152°FSep 2152°F
The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

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 Sitka typically lasts for 6.8 months (209 days), from around April 8 to around November 3, rarely starting before March 20 or after April 27, and rarely ending before October 12 or after November 26.

The month of September in Sitka is reliably fully within the growing season.

Time Spent in Various Temperature Bands and the Growing Season in September in Sitka

Time Spent in Various Temperature Bands and the Growing Season in September in Sitkagrowing seasonSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AugOct100%Sep 1100%Sep 198%Sep 3098%Sep 30100%Sep 11100%Sep 1199%Sep 2199%Sep 2190%Oct 1290%Oct 12very coldcoldcoolfreezingcomfortable
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 percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

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 Sitka are gradually increasing during September, increasing by 106°F, from 560°F to 666°F, over the course of the month.

Growing Degree Days in September in Sitka

The average growing degree days accumulated over the course of September, with 25th to 75th and 10th to 90th percentile bands.

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 Sitka is decreasing during September, falling by 1.4 kWh, from 3.1 kWh to 1.7 kWh, over the course of the month.

Average Daily Incident Shortwave Solar Energy in September in Sitka

Average Daily Incident Shortwave Solar Energy in September in SitkaSep1122334455667788991010111112121313141415151616171718181919202021212222232324242525262627272828292930300 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWhAugOctSep 13.1 kWhSep 13.1 kWhSep 301.7 kWhSep 301.7 kWhSep 112.6 kWhSep 112.6 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

For the purposes of this report, the geographical coordinates of Sitka are 57.053 deg latitude, -135.331 deg longitude, and 30 ft elevation.

The topography within 2 miles of Sitka contains large variations in elevation, with a maximum elevation change of 2,411 feet and an average elevation above sea level of 274 feet. Within 10 miles contains large variations in elevation (4,806 feet). Within 50 miles also contains extreme variations in elevation (58,976 feet).

The area within 2 miles of Sitka is covered by trees (49%), water (37%), and sparse vegetation (12%), within 10 miles by water (45%) and trees (39%), and within 50 miles by water (61%) and trees (27%).

This report illustrates the typical weather in Sitka, 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Sitka.

For each station, the records are corrected for the elevation difference between that station and Sitka 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 Sitka is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Sitka 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 Sitka 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.

Other 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.

Disclaimer

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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