Last updated: February 24, 2025
Saint Helens, located in the United States, experiences a dynamic September marked by a temperature range that peaks at a toasty 35°C (95°F) and dips to a cool 6°C (43°F). The month offers an average temperature of 17°C (63°F), providing a pleasant climate for outdoor activities. However, residents should be prepared for occasional rainfall, as 90 mm (3.6 in) of precipitation falls over 9 days, contributing to a relatively humid environment with an average humidity of 71%. Whether basking in the warmth or enjoying the refreshing rain, September in Saint Helens presents a blend of temperate weather and lush landscapes.
In September, Saint Helens, United States, transitions into autumn with temperatures that strike a comfortable balance. The month typically sees minimums around 6°C (43°F), and average highs reaching 35°C (95°F), creating pleasant days that invite outdoor activities. Notably, the average temperature sits at a mild 17°C (63°F), signaling the end of the sweltering summer months while still providing warm afternoons. As the days grow shorter, the cooling trend becomes evident, offering a refreshing change from the heat of August, which maintains maximum temperatures near 39°C (102°F). This shift not only provides a cozy ambiance for local events and gatherings but also highlights the beauty of the area as it gradually embraces the crispness of fall.
In September, Saint Helens experiences a noticeable shift in precipitation patterns as the dry summer months give way to increased rainfall. With 90 mm (3.6 in) of rain over 9 days, this month marks a significant uptick, compared to the scant 11 mm (0.4 in) recorded in August. This transition signifies the arrival of fall, characterized by a mild increase in precipitation that sets the stage for the wetter months ahead. Notably, September's rainfall is higher than that of the preceding summer, indicating a return to the region's more typical weather patterns. As the foliage begins to change, the revitalizing rains help nourish the landscape, making it a picturesque time for both nature enthusiasts and photographers alike.
In September, Saint Helens experiences a notable shift in humidity, dropping to 71%, the lowest level of the year. This decline marks a transition from the summer’s more humid months, such as August with 74% humidity, suggesting a gradual onset of drier air as autumn approaches. Following the peak of summer, where humidity hovers around the mid-80s, the trend indicates a consistent pattern of decreasing humidity leading into fall. As October rolls in, humidity begins to increase again, averaging 81%, hinting at the wet conditions characteristic of the region during the later months of the year. This cyclical pattern underscores Saint Helens' seasonal humidity fluctuations, making September a distinct turning point before the moisture returns in the fall.
As September rolls into Saint Helens, the UV Index reflects a notable shift in sun exposure, peaking at 7, which signifies high risk for unprotected skin. Following the intense rays of the summer months, when the UV Index soared to 10, September offers a brief respite with a burn time of 25 minutes. This transition indicates a reduction in immediate sun intensity compared to August's very high levels, but caution is still advised. It's a perfect time for outdoor enthusiasts to enjoy the early fall scenery while being mindful of skin protection. For detailed insights into UV levels throughout the year, check out Saint Helens UV Index.
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As September rolls into Saint Helens, the fading glow of summer lingers with 268 hours of sunshine, providing a gentle transition into autumn. This month still boasts a significant amount of sunlight, though it marks a notable decrease compared to the sun-drenched heights of summer, such as 374 hours in July and 335 hours in August. The trend showcases a gradual tapering of daylight as the year progresses, moving from the brilliant brightness of late spring and the peak summer months into the softer, golden hues of fall. With each passing month, Saint Helens witnesses a dance between light and shadow, reminding residents and visitors alike to savor these sunlit moments before winter's embrace begins to settle in.
In September, Saint Helens, United States, experiences a notable 49% chance of sunny weather, making it a delightful time for outdoor activities. This figure reflects a slight decline from the peak summer months, with July boasting a sunlit 73% chance and August a respectable 55%. As the transition into autumn approaches, September offers a pleasant compromise between the vibrant summer sunshine and cooler fall days. Historically, the trend shows that as the year progresses from the dismal winter months to the lively summer, the likelihood of clear skies rises sharply, peaking mid-year before gradually tapering off. Therefore, while September may not guarantee a sun-soaked experience, it certainly holds its own in the spectrum of seasonal weather in Saint Helens.
As summer gives way to autumn in Saint Helens, September brings a transitional shift in daylight, offering approximately 12 hours of sun per day. This marks a noticeable decline from the 14 hours enjoyed in August, reflecting a steady reduction as the months progress towards winter. June and July peak at 15 hours, showcasing the region's vibrant summer days, while January begins the cycle with just 9 hours. The gradual trend highlights the ebb and flow of daylight throughout the year, painting a picture of nature’s rhythm as it prepares for the shorter days ahead.
As September rolls into Saint Helens, the average wind speed settles at a gentle 2.2 m/s (5 mph), aligning closely with the patterns of the preceding months. Following a slight uptick in July, where winds brushed against 2.7 m/s (6 mph), the wind takes a step back, echoing the calm of early spring. This month’s breezy embrace is reminiscent of the more tranquil air seen in April and June, hinting at a transitional phase as we move from summer to autumn. With wind speeds consistently hovering between 2.1 and 2.7 m/s over the year, September’s mild gales make it an ideal time for outdoor activities, offering a perfect balance of comfort and invigoration as nature prepares for the cooler months ahead.
The weather in Saint Helens 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 Saint Helens and find detailed weather information for every month.
September and January present stark contrasts in weather patterns. In September, temperatures range from a mild 6°C (43°F) to a warm 35°C (95°F), with an average of 17°C (63°F), making it a pleasant month overall. However, it experiences moderate precipitation at 90 mm (3.6 in) over about 9 days, paired with a humidity level of 71%. In contrast, January offers a much colder climate, with temperatures dipping as low as -14°C (7°F) and averaging only 5°C (41°F). It is significantly wetter, accumulating 205 mm (8.1 in) of precipitation over 17 days, and features higher humidity at 85%. For a detailed look at January weather, you can explore Saint Helens weather in January.
September and February present a striking contrast in weather conditions. In September, temperatures range from a cool 6°C (43°F) to a warm maximum of 35°C (95°F), with an average of 17°C (63°F), making it a generally warmer month. However, it also experiences moderate precipitation, totaling 90 mm (3.6 in) over about 9 days. In contrast, February is much colder, with temperatures dipping as low as -7°C (19°F) and peaking at a milder 17°C (62°F), leading to a chilly average of only 4°C (40°F). This month sees a significantly higher precipitation level of 205 mm (8.1 in) across 20 days, along with increased humidity at 84%. For a detailed overview of February weather specifically, you can visit Saint Helens weather in February.
When comparing the weather in September and March, notable differences emerge in temperature and precipitation patterns. September experiences more temperate conditions, with average temperatures ranging from a low of 6°C (43°F) to a high of 35°C (95°F), and only 90 mm (3.6 in) of rain spread over 9 days, contributing to a humidity level of 71%. In contrast, March is significantly cooler, with temperatures dipping as low as -3°C (27°F) and averaging around 7°C (45°F), while maximum temperatures reach 22°C (73°F). March also sees a higher amount of rainfall, totaling 163 mm (6.4 in) over 18 days, and a higher humidity level of 85%. For more details, visit Saint Helens weather in March.
When comparing the weather in September and April, significant differences in temperature and precipitation are evident. September enjoys warmer temperatures, with minimums around 6°C (43°F) and highs reaching up to 35°C (95°F), while April starts cooler, with temperatures ranging from a minimum of -1°C (30°F) to a maximum of 29°C (85°F). Precipitation levels are higher in April, totaling 140 mm (5.5 in) over 16 days, contrasted with September's 90 mm (3.6 in) over just 9 days. Additionally, April tends to be more humid, boasting an average of 83% humidity compared to September's 71%. For more detailed insights on April's weather, visit Saint Helens weather in April.
When comparing the weather in September and May, September generally experiences warmer temperatures, with an average of 17°C (63°F) and a maximum reaching up to 35°C (95°F). In contrast, May's average temperature is lower at 14°C (57°F), peaking at 32°C (90°F). September also tends to be drier, with 90 mm (3.6 in) of precipitation over 9 days, compared to May's 73 mm (2.9 in) of rainfall spread across 11 days. Furthermore, humidity levels are slightly lower in September at 71%, compared to May's 83%. For a more detailed look, you can check Saint Helens weather in May.
In comparing the weather between September and June, we notice some interesting contrasts. Both months share a minimum temperature of 6°C (43°F) and an average of 17°C (63°F). However, June can see maximum temperatures soar to an impressive 45°C (113°F), which is significantly higher than September's peak of 35°C (95°F). Additionally, September experiences slightly more rainfall, with 90 mm (3.6 in) of precipitation over 9 days, compared to June's 62 mm (2.5 in) over the same number of days. Humidity levels are also higher in June at 83%, compared to 71% in September. For a detailed look at what to expect, you can visit Saint Helens weather in June.
When comparing the weather in September and July, we see notable differences in temperature and precipitation patterns. September offers a broader temperature range with minimums dropping to 6°C (43°F) and maximums reaching up to 35°C (95°F), averaging around 17°C (63°F). In contrast, July has slightly higher average temperatures, with a minimum of 8°C (46°F) and maximums peaking at 37°C (99°F), averaging 20°C (68°F). Precipitation in September is significantly higher at 90 mm (3.6 in) over 9 days, compared to July’s much drier conditions with only 9 mm (0.3 in) over 2 days. Additionally, July tends to be more humid, with humidity levels at 82%, while September sees a decrease to 71%. For specific details about July weather, you can visit Saint Helens weather in July.
In comparing the weather of September and August, we see notable differences in temperature and precipitation. September experiences a wider range of temperatures with a minimum of 6°C (43°F) and a maximum of 35°C (95°F), while August tends to be warmer, with a minimum of 8°C (47°F) and a maximum of 39°C (102°F). Additionally, September is much wetter, receiving 90 mm (3.6 in) of precipitation over 9 days, compared to August's only 11 mm (0.4 in) over just 2 days. Humidity levels are relatively similar, with September at 71% and August slightly higher at 74%. For a more detailed look at August's weather, you can check Saint Helens weather in August.
September and October present stark contrasts in weather. In September, temperatures start off relatively warm, with an average of 17°C (63°F) and a maximum reaching 35°C (95°F), while the minimum temperature hovers around 6°C (43°F). However, October brings a significant drop in temperatures, with an average of 11°C (52°F) and a maximum of 26°C (78°F), along with colder nights that can dip to -2°C (29°F). Additionally, October experiences increased precipitation, totaling 149 mm (5.9 in) over 13 days, compared to September's 90 mm (3.6 in) over 9 days. Humidity also rises slightly in October to 81%, making the air feel more damp compared to the 71% observed in September. For a detailed look at October weather in a specific location, check out Saint Helens weather in October.
September and November exhibit striking differences in weather patterns. In September, temperatures range from a mild minimum of 6°C (43°F) to a warm maximum of 35°C (95°F), with an average of 17°C (63°F). The month sees 90 mm (3.6 in) of precipitation over about 9 days, maintaining a humidity level of 71%. In contrast, November brings much colder conditions, with temperatures dropping to a minimum of -3°C (27°F) and an average of just 7°C (46°F). The maximum temperature reaches only 18°C (64°F). Rainfall significantly increases to 209 mm (8.2 in), spread over 18 days, and humidity rises to 87%. For more details on the weather in November, check out Saint Helens weather in November.
September and December present notably different weather patterns. In September, temperatures range from a mild 6°C (43°F) at night to a warm 35°C (95°F) during the day, with an average of 17°C (63°F). The month experiences a total precipitation of 90 mm (3.6 in) over about 9 days, combined with a moderate humidity level of 71%. In contrast, December brings much colder conditions, with temperatures dropping to a minimum of -5°C (23°F) and peaking at just 15°C (59°F), resulting in a chilly average of 5°C (41°F). Additionally, December sees increased rainfall, accumulating 224 mm (8.8 in) over approximately 20 days, along with higher humidity at 87%. For more details on December weather, you can view Saint Helens weather in December.
September in Saint Helens marks a transition to cooler, more comfortable weather compared to the sweltering heat of summer months. With an average temperature of 17°C (63°F), this month provides a pleasant reprieve from July and August's highs. While occasional precipitation contributes to the overall humidity, resulting in an average of 71%, the days are still predominantly mild. The blend of warm afternoons and cooler evenings makes September an ideal time to enjoy the natural beauty of the region. For a more detailed look into the weather patterns throughout the year, visit Saint Helens Climate.