September Weather in Port Townsend, United States

Last updated: February 24, 2025

September in Port Townsend, United States, offers a mild climate characterized by a maximum temperature reaching 24°C (76°F) and an average of 15°C (59°F). As the season transitions into autumn, the minimum temperatures can dip to 9°C (48°F), prompting a cozy atmosphere. With 129 mm (5.1 in) of rainfall across 15 days, this month sees a fair amount of precipitation, contributing to the region's lush greenery. The humidity levels average around 74%, creating a refreshing feel that enhances the charm of this coastal town. Whether enjoying the stunning vistas or exploring local attractions, visitors can expect a blend of vibrant scenery and invigorating weather throughout September.

September Temperature in Port Townsend

As summer transitions into autumn, September temperatures in Port Townsend present a charming blend of warmth and coolness. The month begins with a comfortable average of 15°C (59°F), peaking at 24°C (76°F), inviting outdoor enthusiasts to enjoy the lingering sunshine. Nighttime reveals a crispness with a minimum of 9°C (48°F), signaling the impending change of seasons. This gradual cooling marks a notable shift from the warmth of summer months, where July and August averaged around 17°C (63°F). Thus, September provides a beautiful balance, appealing to those who relish the crisp air while still holding onto the vestiges of summer’s warmth.

September Weather in Port Townsend: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Port Townsend, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends.
JanFebMarAprMayJunJulAugSepOctNovDec434144485458626359524743
Data source: Temperature data for Port Townsend 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 Port Townsend

September in Port Townsend marks a transition as summer gradually yields to fall, bringing a notable increase in precipitation. With 129 mm (5.1 in) of rainfall observed over 15 days, this month stands out as wetter than the preceding dry months of July and August, which saw only 58 mm (2.3 in) and 51 mm (2.0 in), respectively. However, September still falls short of the heavier rains typical of October and November, which are known for their consistent downpours. This uptick in precipitation heralds the onset of the rainy season, setting the stage for the lush, vibrant landscapes that characterize the Pacific Northwest in autumn. As the days shorten and temperatures cool, Port Townsend prepares for the wetter months ahead.

September Precipitation Trends in Port Townsend

The chart displays monthly precipitation patterns in Port Townsend, 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.
JanFebMarAprMayJunJulAugSepOctNovDec160157131124911265851129155187187
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Port Townsend

As summer transitions to fall, September brings a slight dip in humidity in Port Townsend, with levels averaging around 74%. This decrease follows the summer peak in August at 73%, marking the tail end of the warm, drier months. The trend reveals a gradual climb back towards the peak winter humidity, as seen in October with 83% and then soaring to 86% and 87% in the following months. The overall pattern highlights a humid climate influenced by seasonal shifts, with September serving as a gentle bridge between the warmth of summer and the moisture-laden months ahead.

September Average Humidity in Port Townsend

This chart illustrates the average monthly humidity levels in Port Townsend, 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%84%85%83%84%84%82%73%74%83%86%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Port Townsend

September in Port Townsend experiences a UV Index of 7, indicating a shift to the high exposure category. This marks a gradual decline from the peak summer months, where the UV Index soared to 9 in both June and July. While the intensity of UV radiation lessens compared to August's 8, it's essential to remain vigilant, as the burn time drops to 25 minutes. As the seasons change, individuals should continue to protect their skin when outdoors, aligning with the broader trend of increasing sun strength during the summer months before tapering off into fall. For more insights on UV exposure in the area, visit Port Townsend UV Index.

Maximum UV Index Levels in Port Townsend for September

The chart shows the monthly maximum UV Index (UVI) for Port Townsend 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.
JanFebMarAprMayJunJulAugSepOctNovDec235689987522
Data source: Port Townsend 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 Port Townsend

As summer gracefully transitions into fall, September in Port Townsend showcases a delightful 262 hours of sunshine, marking a significant decline from July's peak but still offering a warm and inviting atmosphere. This month reflects a trend seen throughout the year, where sunlight gradually increases to a summer high before tapering off into the cooler months. With sunlight peaking in July at 382 hours, September's golden hues provide a gentle reminder of the warmth that preceded it, while October and November signal a retreat, bringing shorter, cloudier days. The shift from abundant summer light to the mellow tones of autumn allows residents and visitors alike to savor the beauty of the changing seasons, deeply intertwined with Port Townsend's coastal charm.

Monthly Sunshine Duration in Port Townsend: September Highlighted

The September sunshine duration represents the total number of hours Port Townsend 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.
JanFebMarAprMayJunJulAugSepOctNovDec84h141h213h243h329h339h382h344h262h197h126h97h
Data source: Port Townsend September Sunshine duration data generated using information from the Copernicus Climate Change Service.

Chance of Sun in Port Townsend During September

September in Port Townsend marks a transitional period where the likelihood of sunny weather sees a dip, with only a 36% chance of sunshine. This decrease follows the summer months, which boast the highest probabilities, peaking in July at 59%. As the vibrant summer days wane, September retains a sense of warmth but introduces more variability in weather patterns. Although this coastal town still enjoys pleasant days, the trend indicates a gentle shift towards increased cloud cover and cooler temperatures, setting the stage for the approaching autumn. Overall, while the sunshine may not be as dependable, September offers lingering glimpses of summer amidst the encroaching fall.

Percentage of Sunny Days in September in Port Townsend

The chart illustrates the percentage of sunny days in Port Townsend 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 Port Townsend experiences clear skies throughout the year.
JanFebMarAprMayJunJulAugSepOctNovDec15%22%31%49%40%51%59%47%36%25%16%14%
Data source: Port Townsend September chance of sun data, generated using information from the Copernicus Climate Change Service.

Daylight Hours in Port Townsend in September

As summer fades in Port Townsend, September heralds a transition with 12 hours of daylight, marking the gradual retreat of longer days experienced from May through August. Notably, this month presents a gentle decline, following the peak of 15 hours in June and July, leading into the shorter days of fall. The shift from the vibrant, sun-soaked days of summer to the more subdued daylight marks a natural rhythm in the seasons, hinting at the cozy autumn evenings ahead. This trend not only affects outdoor activities but also invites a moment of reflection as the community prepares for the quieter months of October and November, where daylight dips to just 10 and 9 hours, respectively.

Average Daylight Hours in Port Townsend for September

The chart illustrates the variation in daylight duration in Port Townsend throughout the year, with September highlighted. It shows the monthly changes in daylight hours, calculated by summing the hours between sunrise and sunset.
JanFebMarAprMayJunJulAugSepOctNovDec8h 52m10h 15m11h 57m13h 41m15h 11m15h 57m15h 31m14h 10m12h 30m10h 46m9h 14m8h 26m
Data source: Port Townsend daylight hours, calculated by summing the hours between sunrise and sunset for each day.

September Winds in Port Townsend

As summer fades into fall, September in Port Townsend brings a subtle shift in wind patterns, with average speeds reaching 2.8 m/s (6 mph). This moderate breeze is a gentle welcome, showing a slight increase from the calmer summer months of July and August. Interestingly, September's wind speed acts as a bridge to the more vigorous gusts that define the later months, as the town prepares for October's rise to 3.8 m/s (8 mph). Overall, this gradual uptick encapsulates the transitional nature of the season, hinting at autumn's approach while still allowing residents and visitors to enjoy the lingering warmth of summer.

Average September Wind Speed in Port Townsend

The chart displays monthly wind speed patterns in Port Townsend, 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.
JanFebMarAprMayJunJulAugSepOctNovDec4.03.33.32.42.52.62.22.32.8 m/s3.84.34.0
Data source: Port Townsend September wind data, generated using information from the Copernicus Climate Change Service.

How September Weather in Port Townsend Compares to Other Months

The weather in Port Townsend 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 Port Townsend and find detailed weather information for every month.

In comparing September and January weather, one can notice striking differences in both temperature and precipitation. September experiences milder temperatures, with an average of 15°C (59°F) and a maximum of 24°C (76°F), while January offers much cooler conditions, averaging just 6°C (43°F) and peaking at 13°C (55°F). Additionally, September sees approximately 129 mm (5.1 in) of precipitation over 15 days, compared to January’s higher total of 160 mm (6.3 in) over 17 days, making it slightly wetter. Humidity levels also diverge, with September hovering around 74% and January climbing to 86%. For more specific insights on January's weather, you can explore Port Townsend weather in January.

Comparing the weather in September and February reveals a significant shift in temperatures and conditions. September boasts milder temperatures, with a minimum of 9°C (48°F), an average of 15°C (59°F), and a maximum of 24°C (76°F), while February experiences much colder weather, featuring a minimum of -6°C (22°F) and a maximum of 13°C (55°F). In terms of precipitation, February is wetter, with 157 mm (6.2 in) of rain over 21 days compared to September's 129 mm (5.1 in) across 15 days. Additionally, February has a higher humidity level at 84%, compared to September's 74%. For more details, check out Port Townsend weather in February.

In comparing the weather between September and March, we can observe notable differences. September typically enjoys a wider temperature range, with minimums around 9°C (48°F) and maximums reaching up to 24°C (76°F), while March experiences cooler conditions, with minimums dropping to 0°C (32°F) and maximums peaking at 19°C (67°F). Both months see a similar level of precipitation, around 130 mm (5.1 in), but March tends to be wetter with precipitation spread over 18 days compared to September's 15 days. Additionally, March has higher humidity levels at 85%, compared to September's 74%. For a closer look at March's weather specifics, you can visit Port Townsend weather in March.

In comparing the weather of September and April, notable differences emerge. September boasts a higher average temperature of 15°C (59°F) with a maximum of 24°C (76°F), while April's temperatures are cooler, averaging 9°C (49°F) with a high of 20°C (68°F). Precipitation levels are quite similar, with September receiving 129 mm (5.1 in) over 15 days and April slightly less at 124 mm (4.9 in) over 16 days. Additionally, September's humidity sits at 74%, making it less humid than April, which has a higher humidity level of 83%. For more detailed insights on April's weather, you can visit Port Townsend weather in April.

September and May present distinct weather patterns, with September generally being warmer and more humid. In September, temperatures range from a minimum of 9°C (48°F) to a maximum of 24°C (76°F), averaging 15°C (59°F) and showcasing a higher humidity level of 74%. In contrast, May sees cooler temperatures, with a minimum of 5°C (42°F) and a maximum of 22°C (71°F), averaging 12°C (54°F) and having a slightly higher humidity of 84%. Precipitation is also more pronounced in September, with 129 mm (5.1 in) over 15 days, compared to May's 91 mm (3.6 in) over 13 days. For specific insights, you can check Port Townsend weather in May.

When comparing the weather in September to June, we notice several key differences. September typically has a more moderate temperature range, with minimums around 9°C (48°F) and maximums reaching up to 24°C (76°F). In contrast, June experiences a broader temperature spread, with minimums at 8°C (47°F) and maximums soaring to 31°C (88°F). Both months receive a similar amount of precipitation, around 125-129 mm, spread over approximately 15 days; however, June sees slightly higher humidity levels at 84% compared to September's 74%. If you're interested in more specific weather patterns for June, you can check out Port Townsend weather in June.

In comparing the weather of September and July, September typically presents cooler temperatures, with a minimum of 9°C (48°F) and an average of 15°C (59°F), whereas July enjoys slightly warmer conditions, starting from a minimum of 11°C (52°F) and averaging 17°C (62°F). The maximum temperature in both months is similar, with July reaching up to 25°C (77°F) and September peaking at 24°C (76°F). However, September experiences significantly higher precipitation, with 129 mm (5.1 in) over about 15 days, compared to July's 58 mm (2.3 in) across just 10 days. Additionally, the humidity in July is slightly higher at 82% compared to September's 74%. For a closer look at July weather specifics, you can check Port Townsend weather in July.

September weather tends to be cooler compared to August, with minimum temperatures dropping from 11°C (52°F) in August to 9°C (48°F) in September. The average temperature also sees a noticeable decline from 17°C (63°F) to 15°C (59°F), while the maximum temperature decreases from 27°C (81°F) to 24°C (76°F). Additionally, September experiences significantly higher precipitation, with 129 mm (5.1 in) falling over 15 days, compared to August, which records only 51 mm (2.0 in) over 8 days. Interestingly, humidity remains fairly stable between the two months, hovering around 73% in August and slightly increasing to 74% in September. For more detailed information, visit Port Townsend weather in August.

September tends to be warmer than October, with average temperatures ranging from a minimum of 9°C (48°F) to a maximum of 24°C (76°F), compared to October's cooler range of 3°C (38°F) to 21°C (69°F). While both months experience considerable rainfall, October sees slightly more precipitation, totaling 155 mm (6.1 in) over 18 days, compared to September's 129 mm (5.1 in) over 15 days. Additionally, October's humidity rises to 83%, making it feel a bit more damp than September’s 74%. For more detailed insights, check out Port Townsend weather in October.

When comparing the weather in September and November, notable differences emerge. September tends to be milder with an average temperature of 15°C (59°F) and daytime highs reaching up to 24°C (76°F). In contrast, November sees a significant drop, with average temperatures around 8°C (47°F) and maximums only reaching 16°C (61°F). Additionally, precipitation increases from 129 mm (5.1 in) over 15 days in September to 187 mm (7.4 in) over 20 days in November, indicating a wetter climate as the year progresses. The humidity also rises from 74% in September to 86% in November, contributing to a chillier feel during the latter month. For more detailed insights, check Port Townsend weather in November.

In September, the weather tends to be milder, with temperatures ranging from a minimum of 9°C (48°F) to a maximum of 24°C (76°F) and an average temperature of 15°C (59°F). The month sees around 129 mm (5.1 in) of precipitation spread over 15 days, along with a moderate humidity level of 74%. In contrast, December experiences much cooler temperatures, featuring a minimum of -5°C (23°F), an average of 6°C (43°F), and a maximum of only 13°C (55°F). This winter month is also wetter, with 187 mm (7.4 in) of precipitation across 21 days, and humidity levels rise to 87%. For more detailed insights into December weather, you can check out Port Townsend weather in December.

Compare Port Townsend's Climate with Cities Worldwide

Conclusion: What to Expect From September Weather in Port Townsend

As summer transitions into autumn, September in Port Townsend offers a unique weather experience that sets it apart from other months. Temperatures cool down significantly, creating a mild atmosphere that embraces both warmth and crispness. While the humidity remains relatively high, the increase in rainfall reflects the approaching fall, with more frequent showers than the dry summer months. This shift not only enhances the lush landscapes of the area but also invites visitors to explore the town’s natural beauty under colorful foliage. For detailed information on the climate patterns throughout the year, visit Port Townsend Climate.