September Weather in Ketchikan, United States

Last updated: February 24, 2025

As September unfolds in Ketchikan, United States, the weather presents a blend of mild temperatures and significant precipitation. The maximum temperature can reach a pleasant 19°C (67°F), while the average hovers around 12°C (55°F), dropping to a cool 8°C (46°F) at night. Humidity levels soar at an impressive 92%, contributing to the lush, vibrant surroundings. This month sees approximately 302 mm (11.9 in) of rain over 17 days, making it one of the wetter months. Residents and visitors alike are advised to embrace the enchanting, yet sometimes unpredictable, conditions that define Ketchikan's September.

September Temperature in Ketchikan

In September, Ketchikan begins to transition from the warmth of summer into the cooler embrace of autumn. With minimum temperatures around 8°C (46°F) and averages reaching 12°C (55°F), there's a noticeable drop from the peak summer warmth, where highs could hit 22°C (72°F). As the month progresses, the maximum temperatures gently decline to about 19°C (67°F), signaling a shift in the season. This month strikes a balance, offering pleasant conditions for outdoor activities, while the crispness in the air hints at the impending fall. Overall, September showcases a lovely blend of lingering summer charm and the first whispers of autumn, making it a delightful time to experience Ketchikan's stunning natural beauty.

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

The chart illustrates September temperature patterns in Ketchikan, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec373538424852575854474238
Data source: Temperature data for Ketchikan 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 Ketchikan

September in Ketchikan continues the trend of high precipitation, matching August's impressive total with 302 mm (11.9 in) of rainfall over 17 days. This significant amount underscores the city's reputation for wet weather as it transitions into the more intense fall months. Following September, October sees a further increase with 331 mm (13.0 in) expected, indicative of the typical escalation in precipitation as winter approaches. The consistent moisture not only shapes Ketchikan’s lush landscapes but also highlights the rhythm of the seasons, where the rainfall peaks in the latter part of the year, paving the way for the even wetter November and December.

September Precipitation Trends in Ketchikan

The chart displays monthly precipitation patterns in Ketchikan, 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.
JanFebMarAprMayJunJulAugSepOctNovDec306168221218141216162302302331410345
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Ketchikan

As summer transitions into fall, September in Ketchikan maintains a high level of humidity at 92%, mirroring the peak levels observed in August. This marks a continuation of the moist air typical of the late summer months, with July and August also showcasing considerable humidity, recorded at 90% and 92% respectively. Interestingly, the humidity begins to drop gradually after September, with October seeing a slight decrease to 91%. Overall, Ketchikan experiences a pattern of higher humidity during the summer months, which then slightly alleviates as autumn progresses, setting the stage for more refreshing, crisper air in the coming months.

September Average Humidity in Ketchikan

This chart illustrates the average monthly humidity levels in Ketchikan, 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.
JanFebMarAprMayJunJulAugSepOctNovDec86%85%84%85%81%81%90%92%92%91%87%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Ketchikan

As September arrives in Ketchikan, the UV Index reflects a moderate level of exposure with a reading of 5, allowing for a burn time of approximately 30 minutes. This marks a transition from the high levels experienced in the summer months of July and August, where sun safety was paramount due to the very high UV exposure. Interestingly, this reduction in UV intensity signals the onset of autumn, reminding residents and visitors alike to adjust their sun protection habits accordingly. A trend of decreasing UV levels will continue into October and November, emphasizing the importance of seasonal awareness. For more details on UV exposure and safety recommendations, visit Ketchikan UV Index.

Maximum UV Index Levels in Ketchikan for September

The chart shows the monthly maximum UV Index (UVI) for Ketchikan 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.
JanFebMarAprMayJunJulAugSepOctNovDec123567875311
Data source: Ketchikan 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 Ketchikan

As autumn approaches, September in Ketchikan brings a gentle transition in sunlight, boasting 184 hours of bright, cheerful days. While this marks a noticeable decline from the sun-drenched peak of July, which shines for a remarkable 248 hours, it is still a substantial amount compared to the darker months ahead. The gradual decrease in daylight hours begins in August with 224 hours, setting the stage for the seasonal shift. This ebbing of sunlight serves as a poignant reminder of the changing seasons, as residents and visitors alike savor the last warm rays before October ushers in a more subdued 132 hours of daylight, curling ever closer to winter's embrace. As nature’s palette transforms with hues of gold and crimson, September remains a sweet spot for those seeking a balance between summer’s lingering glow and autumn’s mellow charm.

Monthly Sunshine Duration in Ketchikan: September Highlighted

The September sunshine duration represents the total number of hours Ketchikan 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.
JanFebMarAprMayJunJulAugSepOctNovDec48h128h174h216h245h232h248h224h184h132h70h63h
Data source: Ketchikan September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Ketchikan During September

In Ketchikan, September typically ushers in cooler temperatures and a notably lower chance of sunny weather, with only a 10% likelihood of clear skies. This dip in sunshine marks a shift from the relatively brighter summer months, where August offered a modest 31% chance of sun. As the seasons transition, the trend reveals that late summer and early fall in Ketchikan are often characterized by increasing cloud cover and precipitation, making September the time to prepare for more overcast skies. While the allure of sunshine may fade, this period offers a unique charm to explore the region's stunning landscapes in a different light.

Percentage of Sunny Days in September in Ketchikan

The chart illustrates the percentage of sunny days in Ketchikan 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 Ketchikan experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec20%28%18%41%15%27%27%31%10%22%17%38%
Data source: Ketchikan September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Ketchikan in September

As summer fades into autumn, September in Ketchikan marks a gradual transition in daylight duration, offering about 12 hours of daylight. This seasonal shift reflects a downward trend from the 17 hours experienced in June and 16 hours in July, as the long summer days give way to shorter ones. With August still providing a generous 14 hours, September serves as a gentle reminder of the approaching winter months. Following this, daylight continues to decrease, with October bringing just 10 hours and November a mere 8 hours. This rhythm of longer days in summer followed by a gradual decline beautifully showcases Ketchikan's unique relationship with light throughout the year.

Average Daylight Hours in Ketchikan for September

The chart illustrates the variation in daylight duration in Ketchikan throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec7h 48m9h 40m11h 55m14h 13m16h 15m17h 20m16h 43m14h 51m12h 38m10h 21m8h 17m7h 10m
Data source: Ketchikan daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Ketchikan

As summer wanes and September arrives in Ketchikan, the winds begin to pick up again, bringing a refreshing change to the air. With an average wind speed of 6.1 m/s (14 mph), September marks a notable increase from the lighter breezes of July and August. This resurgence in wind speed sets the stage for the transition into fall, as gusts become more frequent in the following months. Interestingly, while January boasts the highest average wind of 8.0 m/s (18 mph), September signals a shift back towards brisk conditions, hinting at the brewing storms of autumn. As the days grow shorter and the temperatures drop, Ketchikan's wind provides a reminder of nature's cyclical rhythm, invigorating the landscape and its inhabitants alike.

Average September Wind Speed in Ketchikan

The chart displays monthly wind speed patterns in Ketchikan, 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.
JanFebMarAprMayJunJulAugSepOctNovDec8.06.46.14.44.44.83.74.66.1 m/s6.87.35.4
Data source: Ketchikan September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Ketchikan Compares to Other Months

The weather in Ketchikan 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 Ketchikan and find detailed weather information for every month.

In September, Ketchikan experiences milder temperatures with a minimum of 8°C (46°F) and an average of 12°C (55°F), peaking at 19°C (67°F). The weather is quite wet, with 302 mm (11.9 in) of precipitation over 17 days and high humidity at 92%. In contrast, January brings much colder conditions, where temperatures plummet to a minimum of -10°C (15°F) and an average of 3°C (37°F), reaching a maximum of 8°C (47°F). Although both months see a similar amount of precipitation—with January recording 306 mm (12.1 in) over 18 days—the humidity is slightly lower at 86%. For more detailed information, you can check Ketchikan weather in January.

In September, Ketchikan experiences milder temperatures with averages around 12°C (55°F) and maximums reaching up to 19°C (67°F), while February sees a significant drop, with average temperatures plummeting to just 2°C (36°F) and maximums only reaching 8°C (47°F). September is characterized by high precipitation levels, receiving a substantial 302 mm (11.9 in) of rain over 17 days, creating a lush environment, whereas February's precipitation is notably lower at 168 mm (6.6 in) over 14 days, often falling as snow. Additionally, the humidity in September is high at 92%, offering a damp chill, while February's humidity is slightly lower at 85%, making the cold feel a bit more piercing. For more detailed insights into the February climate, you can check Ketchikan weather in February.

September and March present contrasting weather patterns in Ketchikan. In September, temperatures range from a mild 8°C (46°F) at night to a comfortable 19°C (67°F) during the day, accompanied by significant rainfall of 302 mm (11.9 in) spread over 17 days, resulting in high humidity levels of 92%. In contrast, March experiences colder temperatures, with a minimum of -4°C (25°F) and a maximum of 14°C (57°F), along with lower precipitation of 221 mm (8.7 in) over 19 days. Despite the reduced rainfall, March boasts a slightly drier atmosphere with a humidity of 84%. For more detailed insights, you can check out the Ketchikan weather in March.

In comparing the weather between September and April, September typically showcases milder temperatures, with an average of 12°C (55°F) compared to April’s cooler average of 6°C (43°F). The maximum temperatures in September can reach up to 19°C (67°F), while April peaks at 14°C (57°F). Precipitation is also more pronounced in September, with 302 mm (11.9 in) over 17 days, compared to April's 218 mm (8.6 in) over 16 days. Humidity levels are slightly higher in September at 92%, versus 85% in April. For more detailed information on April's weather, you can check Ketchikan weather in April.

In comparing the weather patterns of September and May, September tends to be warmer with average temperatures ranging from a minimum of 8°C (46°F) to a maximum of 19°C (67°F), while May features cooler averages, with temperatures fluctuating between 4°C (40°F) and 18°C (65°F). Precipitation levels in September are significantly higher, with 302 mm (11.9 in) recorded over 17 days, compared to May's 141 mm (5.6 in) across 15 days. Additionally, September experiences higher humidity at 92%, whereas May has a lower humidity level of 81%. For a more detailed look at weather conditions during this month, visit Ketchikan weather in May.

In comparing the weather between September and June, September is generally cooler with average temperatures ranging from a minimum of 8°C (46°F) to a maximum of 19°C (67°F), while June features slightly warmer temperatures, with a minimum of 7°C (44°F) and a maximum of 22°C (72°F). September experiences higher precipitation, totaling 302 mm (11.9 inches) over 17 days, compared to June's 216 mm (8.5 inches) over 18 days. Additionally, September has a noticeably higher humidity level of 92%, while June's humidity is more moderate at 81%. For more detailed information about June weather, you can visit Ketchikan weather in June.

In comparing the weather between September and July, we see notable differences in temperature and precipitation. September experiences cooler temperatures, with an average of 12°C (55°F), peaking at 19°C (67°F), while July is generally warmer, with average temperatures around 14°C (57°F) and a maximum of 22°C (71°F). Additionally, September is significantly wetter, receiving 302 mm (11.9 in) of rain over 17 days compared to July's 162 mm (6.4 in) over 14 days. Humidity levels are also slightly higher in September at 92%, in contrast to July's 90%. For more detailed information, check out Ketchikan weather in July.

September weather in Ketchikan is characterized by cooler temperatures compared to August, with minimums dropping from 10°C (50°F) to 8°C (46°F) and maximums decreasing from 22°C (72°F) to 19°C (67°F). Both months experience the same level of precipitation, with 302 mm (11.9 in) falling over 17 days and consistent humidity at 92%. Overall, September marks a transition into cooler days, while August offers slightly warmer and more comfortable conditions. For more details on August's climate, you can check Ketchikan weather in August.

In comparing the weather of September and October, it's evident that both months experience significant rainfall, with October receiving slightly more at 331 mm compared to September's 302 mm. While September boasts milder temperatures with averages around 12°C (55°F) and maximums reaching 19°C (67°F), October's temperatures drop, featuring an average of 8°C (47°F) and a maximum of only 14°C (57°F). Additionally, October sees a slight increase in the number of rainy days, with precipitation recorded on 20 days versus 17 in September. Humidity levels remain similar, hovering around 91-92%. For more detailed insights, you can check Ketchikan weather in October.

September and November weather in Ketchikan presents a striking contrast. In September, temperatures range from a minimum of 8°C (46°F) to a comfortable maximum of 19°C (67°F), with an average of 12°C (55°F). The month experiences significant rainfall, totaling 302 mm (11.9 in) over 17 days, contributing to a high humidity level of 92%. In contrast, November sees much cooler temperatures, with highs of only 11°C (51°F) and lows dipping to freezing at 0°C (32°F), leading to an average of 6°C (43°F). Additionally, November is wetter, accumulating 410 mm (16.1 in) of precipitation across 23 days, while humidity decreases slightly to 87%. For more details, you can check Ketchikan weather in November.

September and December present stark contrasts in weather patterns. September's temperatures range from a mild 8°C (46°F) to a maximum of 19°C (67°F), with significant rainfall totaling 302 mm (11.9 in) over about 17 days and high humidity at 92%. In contrast, December brings colder conditions, with temperatures dropping to a minimum of -10°C (15°F) and an average of 3°C (38°F), alongside a higher precipitation level of 345 mm (13.6 in) spread over 21 days, and slightly lower humidity at 87%. These differences highlight the transition from early fall to the heart of winter. For more information, visit Ketchikan weather in December.

Compare Ketchikan's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Ketchikan

As September rolls into Ketchikan, it marks a notable transition in weather patterns compared to the summer months. The temperatures begin to dip, offering a refreshing change from the warmer days of July and August, settling into a more comfortable range that invites cozy layers. However, September also ushers in significantly increased precipitation, with a marked uptick in rainy days, making it one of the wetter months of the year. Coupled with the high humidity, this time of year presents a crisp, invigorating climate that breathes life into the lush Alaskan landscape. For a deeper dive into what to expect throughout the year in Ketchikan, check out the detailed insights at Ketchikan Climate.