Last updated: August 21, 2025
September in Porvoo, Finland brings a blend of mild and chilly weather, with maximum temperatures reaching up to 24°C (75°F) and dipping to a cooler average of 12°C (53°F). The month can feel particularly crisp, especially with minimum temperatures touching -2°C (29°F). Rainfall is common, accumulating to 63 mm (2.5 in) over 12 days, resulting in a humidity level of 90% that envelops the charming town. Whether you're enjoying the changing leaves or exploring the historic sites, September's unpredictable weather adds a unique charm to Porvoo's atmospheric allure.
In September, Porvoo experiences a gentle transition from the warmth of summer to the crispness of autumn. With minimum temperatures dipping to around -2°C (29°F) and an average of 12°C (53°F), the days remain pleasantly mild, peaking at a comfortable 24°C (75°F). This month stands out as the last hurrah of warmth before the cooler months set in, making it an ideal time for outdoor activities and enjoying the stunning fall foliage. As the warmth wanes, locals and visitors alike begin to sense the approach of winter, but for now, September offers a delightful balance, inviting all to revel in the vibrant seasonal changes.
September in Porvoo, Finland, ushers in a refreshing change as it experiences a notable precipitation of 63 mm (2.5 in) across 12 days. This marks a slight dip from the wetter months of August and July, highlighting a transitional phase as summer shifts to autumn. Although the rainfall is less than the preceding month, it contributes to the overall seasonal charm, often resulting in vibrant foliage against the greying skies. As autumn settles in, the increase in precipitation days prepares the landscape for the more substantial rainfall that follows in October, where a total of 80 mm (3.2 in) is recorded. This rhythm of rainfall not only underscores the region’s climate variability but also sets the stage for the picturesque fall scenery typical of Porvoo.
In September, Porvoo, Finland, experiences a notable shift in humidity, registering at 90%—a significant increase from the summer months. As the vibrant colors of autumn emerge, humidity levels gradually rise from the lower summer averages of 74% in June and 75% in May, marking a transition towards the higher fall and winter values. This pattern mirrors the earlier months of the year, where humidity remained elevated, peaking at a staggering 98% in January. The consistent trend of higher humidity, especially in the latter half of the year, not only reflects the changing seasons but also contributes to Porvoo’s enchanting atmosphere, transitioning from the warmth of summer to the crispness of autumn.
As September unfolds in Porvoo, Finland, the UV Index drops to 4, indicating a moderate exposure category. This marks a gradual decline from the peak summer values of 7 observed in June and July. As the days shorten and temperatures cool, residents and visitors will enjoy 30 minutes of safe sun exposure before the risk of harm increases. This transition reflects a clear trend from the intense UV levels earlier in the summer months, gradually easing back into the more forgiving conditions of fall. For anyone spending time outdoors, it's essential to stay informed about UV levels; check out more details at Porvoo UV Index for safety tips and updates.
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As September unfolds in Porvoo, Finland, the city enjoys a gentle transition from the vibrant warmth of summer to the crispness of autumn. With 289 hours of sunshine, September marks a notable decline from the sunny August, which boasted 408 hours. This gradual drop is part of a broader trend, as the sunlit days steadily diminish from the peaks of June and July, both seeing almost 491 hours of radiant light. Despite the fading daylight, September's warmth lingers, rich with golden hues that embrace the charming cobbled streets and scenic waterways of Porvoo, inviting residents and visitors alike to relish the last touches of summer before the more opaque months of October and November set in.
As summer fades, the chances of sunny weather in September in Porvoo, Finland begin to dwindle, with a sun probability of only 26%. This marks a noticeable decline from the peak sunny days seen in July (57%) and June (53%), as warmer months grant way to the cooler embrace of autumn. Interestingly, September's sunshine likelihood is slightly lower than that of August, which enjoys 27% sunshine, reflecting the gradual shift in seasons. As October approaches, the chances diminish even further, hinting at the cloudy, crisp days that characterize the latter part of the year. Despite September's reduced sunlight, it still offers glimpses of summer's warmth, making it a unique time to experience Porvoo's stunning fall landscapes.
In September, Porvoo, Finland, experiences a gradual shift as daylight begins to wane, offering around 12 hours of daylight. Following the long, bright summer months of June and July, which bask in nearly 18 hours of sunlight, the transition into autumn signals a decrease in light. From August's 15 hours, this decline marks the onset of shorter days ahead. As nature prepares for the cooler months, September provides a balanced blend of light and a glimpse into the encroaching darker days of October, which will see daylight drop to 10 hours. This rhythm of changing daylight not only influences daily life but also paints a captivating backdrop as the seasons evolve in this picturesque Finnish town.
As September rolls into Porvoo, Finland, the coastal breeze brings a subtle shift in the air, with an average wind speed of 3.5 m/s (8 mph). This marks a slight decrease from the gusty heights of summer, where August's winds reached a brisk 3.8 m/s (9 mph). Nevertheless, September's winds retain a refreshing edge, bridging the transition into the cooler months ahead. Looking back, the year saw January kicking off with lighter gusts at 3.4 m/s (8 mph) and peaking in October when winds increase to 4.5 m/s (10 mph), heralding the start of autumn's bolder breezes. Overall, September maintains a sense of calm before the winter chill fully sets in, making it an ideal time to enjoy the serene beauty of Porvoo's landscapes.
Weather in Porvoo varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Porvoo, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present strikingly different weather patterns, reflecting the transition from fall to deep winter. In September, temperatures generally range from a chilly minimum of -2°C (29°F) to a pleasant maximum of 24°C (75°F), with an average of 12°C (53°F). This month sees approximately 63 mm (2.5 in) of precipitation over 12 days and a humidity level of 90%. In stark contrast, January experiences frigid temperatures, with a minimum of -25°C (-13°F), an average of -3°C (27°F), and a maximum of only 8°C (47°F). Precipitation in January amounts to 54 mm (2.1 in) over 11 days, accompanied by even higher humidity at 98%. For a more detailed overview of January weather, visit Porvoo weather in January.
In September, temperatures are significantly milder, with averages around 12°C (53°F) and highs reaching up to 24°C (75°F), making it a pleasant transition from summer to autumn. In contrast, February brings much colder conditions, with average temperatures plummeting to -4°C (25°F) and maximums only reaching 8°C (46°F). While September experiences more precipitation at 63 mm (2.5 in) over 12 days, February has slightly less at 48 mm (1.9 in) over 10 days, but the humidity is notably higher in February at 96%. For those curious about winter weather conditions, you can learn more through this link: Porvoo weather in February.
September and March present striking contrasts in weather conditions. In September, temperatures fluctuate from a minimum of -2°C (29°F) to a pleasant average of 12°C (53°F), peaking at a maximum of 24°C (75°F). The month experiences around 63 mm (2.5 in) of precipitation over 12 days, with humidity levels at 90%. Conversely, March is considerably colder, with temperatures ranging from a minimum of -23°C (-10°F) to an average of -1°C (30°F), and a maximum of only 13°C (55°F). Despite slightly lower precipitation at 49 mm (1.9 in) over the same number of days, March has a higher humidity level at 93%. For a more detailed look at the specific weather patterns, see Porvoo weather in March.
When comparing the weather in September and April, September typically boasts milder temperatures, with an average of 12°C (53°F) and highs reaching up to 24°C (75°F), while April is considerably cooler, with an average temperature of 4°C (40°F) and a minimum of -14°C (7°F). Precipitation levels are slightly higher in September at 63 mm (2.5 in) over about 12 days, compared to April's 48 mm (1.9 in) over 11 days, indicating that September may experience a bit more rain. Additionally, humidity is slightly higher in September at 90%, while April sits at 87%. For more detailed information about April weather, you can visit Porvoo weather in April.
In comparing the weather of September and May, we see distinct differences. September features a broader temperature range with a minimum of -2°C (29°F) and a maximum of 24°C (75°F), showcasing relatively mild days and chilly nights, while May's temperatures dip slightly lower, ranging from -4°C (26°F) to a warmer maximum of 29°C (84°F). Precipitation levels also vary; September receives 63 mm (2.5 in) over 12 days, accompanied by a higher humidity of 90%, making it feel quite damp. In contrast, May sees less rainfall at 50 mm (2.0 in) across 10 days, with a lower humidity level of 75%, leading to a more comfortable overall feel. For a deeper look at May's climate in detail, check out Porvoo weather in May.
In comparing the weather of September and June, September tends to be cooler, with average temperatures ranging from a minimum of -2°C (29°F) to a maximum of 24°C (75°F), while June boasts warmer conditions with temperatures between 2°C (35°F) and 32°C (89°F). September also experiences higher humidity at 90%, contrasting with June's 74%. Additionally, while both months have similar days of precipitation—12 days in September and 11 days in June—September has a slightly higher total rainfall of 63 mm (2.5 in) compared to June's 56 mm (2.2 in). For a more detailed look at the weather in June, you can check out Porvoo weather in June.
In comparing the weather of September and July, September experiences cooler temperatures, with a minimum of -2°C (29°F) and an average of 12°C (53°F), while July boasts warmer conditions with a minimum of 7°C (44°F) and an average of 18°C (65°F). The maximum temperatures in July can reach up to 32°C (89°F), significantly higher than the 24°C (75°F) observed in September. Although both months see around 12 days of precipitation, September has slightly less rainfall at 63 mm (2.5 in) compared to July's 71 mm (2.8 in). Additionally, September's humidity is higher at 90%, which can contribute to a cooler and more damp atmosphere, whereas July enjoys a more comfortable level of 80% humidity. For more details about July weather, you can visit Porvoo weather in July.
In September, the weather is noticeably cooler than in August, with minimum temperatures dropping to -2°C (29°F) compared to August's minimum of 6°C (43°F). The average temperature in September is 12°C (53°F), whereas August enjoys a warmer average of 16°C (62°F) with maximum temperatures reaching 31°C (87°F) in the latter month. Precipitation is slightly lower in September at 63 mm (2.5 in) compared to 78 mm (3.1 in) in August, although both months experience rain on 12 days. Humidity levels also remain high in both months, with September at 90% and August at 85%. For a more detailed look at August weather, you can refer to Porvoo weather in August.
In September, the weather features milder temperatures with a minimum of -2°C (29°F) and an average of 12°C (53°F), peaking at 24°C (75°F). The month sees a total precipitation of 63 mm (2.5 in) over 12 days and a relatively high humidity of 90%.
In contrast, October brings cooler conditions, with a minimum reaching -5°C (23°F) and an average temperature dropping to 7°C (44°F), while the maximum temperature is capped at 17°C (64°F). Precipitation increases to 80 mm (3.2 in) across 15 days, and humidity rises slightly to 94%. For more detailed insights on what to expect, check out Porvoo weather in October.
September and November present a notable shift in weather patterns. In September, temperatures range from a minimum of -2°C (29°F) to a maximum of 24°C (75°F), with an average of 12°C (53°F), offering a more moderate warmth as summer transitions to autumn. However, November brings a significant drop in temperatures, with a minimum of -8°C (18°F), an average of just 3°C (37°F), and a maximum of 12°C (54°F). Both months experience approximately 12 days of precipitation, but September sees slightly more rain with 63 mm (2.5 in) compared to November's 56 mm (2.2 in). Additionally, November accompanies higher humidity, reaching 94%, compared to September's 90%. For a detailed look at weather conditions in November, you can visit Porvoo weather in November.
September and December present contrasting weather conditions. In September, temperatures range from a mild minimum of -2°C (29°F) to a pleasant maximum of 24°C (75°F), with an average of 12°C (53°F). The month experiences 63 mm (2.5 in) of precipitation over 12 days and relatively high humidity at 90%. In stark contrast, December sees much colder temperatures, with a minimum of -20°C (-3°F) and a maximum of just 7°C (44°F), averaging around -1°C (30°F). Additionally, December brings a slight increase in precipitation to 73 mm (2.9 in) over 16 days, along with even higher humidity levels at 96%. For more specific details on December weather, check out Porvoo weather in December.
As September unfolds in Porvoo, the weather transitions dramatically from the warmth of summer to the crisp embrace of autumn. With an average temperature around 12°C, this month is cooler than the preceding summer months, yet still enjoys a few warmer days with highs reaching up to 24°C. The increased likelihood of rain—12 rainy days and a total of 63 mm—casts a different mood compared to the drier summer. Humidity levels soar to 90%, making the air feel brisk and fresh. This enchanting change signals nature’s shift, inviting locals and visitors alike to experience the vibrant colors of fall. For a deeper understanding of seasonal patterns, be sure to explore the Porvoo Climate.