September Weather in Anchorage, United States

Last updated: February 24, 2025

In September, Anchorage experiences a refreshing transition into autumn, with temperatures ranging from a maximum of 18°C (65°F) to a cooler minimum of -1°C (31°F). The average temperature settles at a mild 11°C (52°F), providing a crisp feel in the air. The month is marked by substantial precipitation, totaling 109 mm (4.3 in) spread over about 17 days, contributing to a humid environment with levels soaring at 97%. As the days grow shorter and the leaves begin to change, September in Anchorage offers a unique blend of cool climates and vibrant landscapes.

September Temperature in Anchorage

As September arrives in Anchorage, the city begins to shed its warm summer attire, signaling the transition to autumn. The temperatures range from a chilly -1°C (31°F) at night to a mild max of 18°C (65°F) during the day, creating a crisp yet comfortable atmosphere. With an average of 11°C (52°F), September provides a gentle reprieve from the sweltering summer heat while hinting at the colder months ahead. This period marks a clear shift as nighttime temperatures drop, reminiscent of the biting cold of winter that looms just around the corner. The gradual cooling trend complements the changing colors of the foliage, making it a picturesque time for nature lovers and outdoor enthusiasts alike.

September Weather in Anchorage: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Anchorage, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec192327374756605952412725
Data source: Temperature data for Anchorage generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Anchorage

In September, Anchorage experiences a significant shift in its weather patterns, marked by 109 mm (4.3 in) of precipitation over 17 days. This month showcases nearly the same level of rainfall as August, suggesting a continuation of the late summer downpours. However, September's precipitation days are notably increased, indicating a more persistent drizzly climate as fall approaches. As the month progresses, Anchorage transitions towards its wetter season, setting the stage for higher rainfall in October, which averages 129 mm (5.1 in). This trend highlights the gradual buildup of moisture that characterizes the onset of autumn in the region.

September Precipitation Trends in Anchorage

The chart displays monthly precipitation patterns in Anchorage, with values for each month alongside September's data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September's conditions compare to those of other months.
JanFebMarAprMayJunJulAugSepOctNovDec525244355348731121091298799
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Anchorage

In September, Anchorage experiences a notable humidity level of 97%, continuing the trend of high moisture that characterizes the late summer and early fall months. This level of humidity follows the peak months of July and August, which boast even higher percentages of 100% and 99% respectively. As the year transitions, humidity remains remarkably elevated, with January and February showcasing a consistent 95%. While humidity slightly decreases in the spring months, it bounces back in the autumn, indicating that Anchorage’s weather is often cloaked in a veil of dampness. This pattern highlights the region's distinct maritime climate, where moisture hangs heavily in the air throughout much of the year.

September Average Humidity in Anchorage

This chart illustrates the average monthly humidity levels in Anchorage, with September's data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, allowing you to see how September's humidity levels compare to other months.
JanFebMarAprMayJunJulAugSepOctNovDec95%95%90%82%85%95%100%99%97%93%97%98%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Anchorage

As September rolls into Anchorage, the UV Index holds steady at 4, indicating moderate exposure levels, similar to the peaks seen in April and May. This month maintains a burn time of approximately 30 minutes, urging residents to protect their skin during outdoor activities. Compared to the summer peaks of July with its higher index of 7, September sees a slight decline, signaling the gradual transition into fall. With October ushering in lower UV levels, this month offers a last chance for sun enthusiasts to soak up some rays before the colder months arrive. For more details on UV trends and safety tips, visit Anchorage UV Index.

Maximum UV Index Levels in Anchorage for September

The chart shows the monthly maximum UV Index (UVI) for Anchorage in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec113456754211
Data source: Anchorage September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

September Sunshine in Anchorage

As summer gracefully transitions into autumn, September in Anchorage serves as a beautiful reminder of the vibrant sunlight that graced the city during the warmer months. This month basks in 191 hours of sunshine, a noticeable decline from the peak of 319 hours in June, yet still abundant compared to the dimming days ahead. The warm glow of early fall is especially inviting as it holds onto the tail end of summer, offering a stark contrast to the chilly darkness of winter, which looms with only 39 hours of sunlight in December. With a steady decrease that began in August, September captures a bittersweet blend of lingering warmth and the imminent embrace of shorter days, painting a vivid picture of Anchorage's dynamic seasonal rhythms.

Monthly Sunshine Duration in Anchorage: September Highlighted

The September sunshine duration represents the total number of hours Anchorage experiences direct sunlight during the month of September, excluding cloudy or obstructed periods. This chart compares the sunshine duration of September with the other months of the year.
JanFebMarAprMayJunJulAugSepOctNovDec56h122h207h264h287h319h300h267h191h127h94h39h
Data source: Anchorage September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Anchorage During September

In September, Anchorage experiences a 30% chance of sunny weather, marking a slight dip from the summer months. As the year progresses, we see a notable fluctuation in sun likelihood, with earlier months like April peaking at 50%. This trend suggests that while early fall can still deliver pleasant days, the overall atmosphere shifts towards gloomier conditions as winter approaches. Interestingly, September's sun probability mirrors July and August, both settling around the low thirties, indicating that even as summer winds down, there's still a fighting chance for that elusive sunshine before autumn takes hold.

Percentage of Sunny Days in September in Anchorage

The chart illustrates the percentage of sunny days in Anchorage throughout the year, with September highlighted. It highlights the variation in sunshine across each month and provides an overview of the typical frequency of sunny days, offering insights into how often Anchorage experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec25%33%39%50%32%30%23%34%31%19%36%24%
Data source: Anchorage September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Anchorage in September

As summer fades into autumn, September in Anchorage, United States, offers a gentle transition in daylight hours, providing about 12 hours of sunlight. This marks a noticeable shift from the exuberant 19 hours of daylight in June, ushering in the softer hues of fall. Following the vibrant summer months, where daylight peaked in both June and July, September's daylight duration gradually narrows, shifting the landscape from bright late nights to earlier twilight. By this time, the days are still relatively long compared to the winter months ahead, but the trend indicates a clear descent into the darker seasons, with October bringing only 9 hours of daylight. This rhythm of daylight underscores the dramatic seasonal changes that define Anchorage's unique Arctic climate, inviting both reflection and anticipation of the beauty that the shorter days will bring.

Average Daylight Hours in Anchorage for September

The chart illustrates the variation in daylight duration in Anchorage throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec6h 28m9h 1m11h 53m14h 49m17h 36m19h 14m18h 17m15h 40m12h 47m9h 53m7h 8m5h 32m
Data source: Anchorage daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Anchorage

As summer wanes and September embraces Anchorage, the average wind speed picks up slightly to 2.4 m/s (5 mph), marking a gentle shift from the calmer breezes of the preceding months. This increase hints at the changing season, as the winds begin to whisper tales of autumn ahead. Throughout the year, the city experiences varied gusts, peaking in the colder months, but September stands out as a transitional time—breathing life into the crisp air while maintaining a soothing warmth reminiscent of summer. The gradual rise in wind patterns from August, paired with the upcoming chill in October, sets the stage for a dance between the lingering warmth of summer and the encroaching coolness of fall.

Average September Wind Speed in Anchorage

The chart displays monthly wind speed patterns in Anchorage, with values for each month shown alongside September's data, which is highlighted for easy comparison. It illustrates the average wind speed, offering insights into how September's wind conditions compare to the rest of the year.
JanFebMarAprMayJunJulAugSepOctNovDec3.02.72.32.51.91.81.82.02.4 m/s2.52.42.6
Data source: Anchorage September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Anchorage Compares to Other Months

The weather in Anchorage changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of September's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Anchorage and find detailed weather information for every month.

September and January present stark contrasts in weather conditions. In September, temperatures are mild, ranging from a minimum of -1°C (31°F) to a maximum of 18°C (65°F), with an average of 11°C (52°F). The month experiences substantial rainfall, totaling 109 mm (4.3 in) over 17 days, and the humidity is quite high at 97%. In contrast, January plunges into much colder temperatures, with a minimum of -25°C (-12°F) and a maximum of only 7°C (44°F), leading to an average temperature of -7°C (19°F). Precipitation decreases significantly to 52 mm (2.1 in) across 10 days, while humidity remains nearly as high at 95%. This drastic difference highlights the transition from the mellow, wet days of September to the harsh, frigid climate of January. For a deeper look at January weather in Anchorage, visit Anchorage weather in January.

In September, the weather in Anchorage features a mild average temperature of 11°C (52°F), with highs reaching up to 18°C (65°F) and lows around -1°C (31°F). This month experiences significant precipitation, totaling 109 mm (4.3 in) over about 17 days, alongside high humidity at 97%. In contrast, February brings much colder conditions, with an average temperature of -5°C (23°F), ranging from a low of -18°C (0°F) to a high of 5°C (42°F). Precipitation is less frequent at 52 mm (2.0 in) over 10 days, and humidity remains high at 95%. For more detailed information, check out Anchorage weather in February.

In comparing the weather of September and March, it's evident that September offers milder temperatures, with averages around 11°C (52°F) and highs reaching up to 18°C (65°F), while March is notably colder, featuring average temperatures of -3°C (27°F) and maximums only reaching 8°C (46°F). Precipitation levels in September are significantly higher, at 109 mm (4.3 in) over 17 days, compared to March's 44 mm (1.7 in) spread across just 9 days. Additionally, September experiences high humidity levels at 97%, whereas March's humidity is slightly lower at 90%. For more detailed insights, you can explore Anchorage weather in March.

When comparing the weather in September and April, it’s evident that September enjoys milder temperatures, with average highs reaching up to 18°C (65°F) while April is cooler, averaging around 3°C (37°F). Notably, September experiences higher humidity at 97%, compared to April’s 82%, contributing to a more damp sensation. Additionally, September sees significantly more precipitation, totaling 109 mm (4.3 in) over 17 days, whereas April has much less with only 35 mm (1.4 in) across 8 days. For a more detailed overview of April's climate, you can visit Anchorage weather in April.

In September, the weather in Anchorage tends to be cooler and wetter compared to May. The average temperature hovers around 11°C (52°F), with highs reaching up to 18°C (65°F), while the humidity climbs to a high of 97%. This month also sees significantly more precipitation, totaling 109 mm (4.3 in) over 17 days. In contrast, May offers slightly milder conditions, with an average temperature of 8°C (48°F) and a maximum of 19°C (67°F). The total precipitation is notably less at 52 mm (2.1 in) across 11 days, and the humidity is lower at 85%. For a more detailed look at the weather patterns, you can check out Anchorage weather in May.

In comparison to June, September in Anchorage experiences significantly cooler temperatures, with a minimum of -1°C (31°F) and a maximum of 18°C (65°F), compared to June's minimum of 6°C (43°F) and maximum of 25°C (78°F). September also sees more precipitation, totaling 109 mm (4.3 in) over 17 days, while June has just 48 mm (1.9 in) across 12 days. Although both months maintain high humidity levels, September's humidity is slightly higher at 97% compared to June's 95%. For a more detailed insight into June weather, check out Anchorage weather in June.

In comparison to July, September experiences significantly cooler temperatures, with nighttime lows plummeting to -1°C (31°F) compared to July’s mild minimum of 10°C (50°F). The average temperature in September hovers around 11°C (52°F), while July boasts a warmer average of 16°C (61°F) and maximums that can reach as high as 27°C (81°F). Additionally, September tends to be wetter, with 109 mm (4.3 in) of precipitation over 17 days, whereas July sees less rain at 73 mm (2.9 in) across 12 days. Interestingly, despite being one of the wettest months, July has a slightly lower humidity level of 100% compared to September's high humidity of 97%. For more detailed insights, you can check Anchorage weather in July.

September weather in Anchorage marks a noticeable shift from August, with significantly cooler temperatures overall. While August enjoys a milder range from a minimum of 7°C (44°F) to a maximum of 23°C (74°F), September sees a drop with lows dipping to -1°C (31°F) and highs reaching only 18°C (65°F). Both months experience considerable precipitation, with September totaling 109 mm (4.3 in) over 17 days, slightly easing from August's 112 mm (4.4 in) across 15 days. Humidity levels remain high, but September's average of 97% is slightly lower than August's 99%. For a more detailed look at August conditions, you can refer to Anchorage weather in August.

September and October present a noticeable transition in weather conditions. In September, temperatures range from a minimum of -1°C (31°F) to a maximum of 18°C (65°F), with an average of 11°C (52°F). The month experiences 109 mm (4.3 in) of precipitation over 17 days, alongside high humidity levels at 97%. In contrast, October sees cooler temperatures, with a minimum of -7°C (20°F) and a maximum of 14°C (57°F), averaging 5°C (41°F). Interestingly, precipitation increases slightly to 129 mm (5.1 in) across the same number of days, though humidity decreases to 93%. This shift indicates a more pronounced chill as autumn progresses, typical for the region. For more details on specific weather conditions, check out Anchorage weather in October.

September and November in Anchorage present a stark contrast in weather conditions. In September, temperatures range from a chilly minimum of -1°C (31°F) to a pleasant maximum of 18°C (65°F), with an average of 11°C (52°F). The month experiences significant precipitation, totaling 109 mm (4.3 in) over 17 days, while humidity remains high at 97%. By November, however, temperatures drop significantly, with a minimum of -20°C (-4°F), an average of -3°C (27°F), and a maximum of only 7°C (44°F). Precipitation decreases to 87 mm (3.4 in) over 12 days, yet the humidity stays constant at 97%. This transition marks a shift from relatively mild early fall weather to the cold depths of winter. For more information, check out Anchorage weather in November.

September and December present quite contrasting weather conditions. In September, temperatures can range from a chilly -1°C (31°F) to a pleasant 18°C (65°F), with an average of 11°C (52°F). The month experiences a significant amount of precipitation, totaling 109 mm (4.3 in) over 17 days, and the humidity remains high at 97%. In stark contrast, December sees much colder temperatures, with a minimum of -21°C (-6°F) and a maximum of 7°C (44°F), averaging -4°C (25°F). Precipitation decreases slightly to 99 mm (3.9 in) over 16 days, while humidity remains similarly high at 98%. For more detailed information on the weather in December, you can refer to Anchorage weather in December.

Compare Anchorage's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Anchorage

As summer fades, September in Anchorage brings a noticeable change in weather, with cooler temperatures and increased precipitation setting the tone for the fall season. Residents experience a hint of winter on the horizon, as mornings can dip below freezing, while days remain mild. This month is marked by high humidity and frequent rain, resulting in a lush, vibrant landscape that contrasts sharply with the dry months of summer. For those intrigued by how September fits into the broader climatic picture, explore more about the city’s unique weather patterns at Anchorage Climate.