Last updated: August 21, 2025
In September, Lahti, Finland experiences a diverse range of weather conditions, with maximum temperatures reaching up to 23°C (73°F) and an average of 11°C (52°F). As autumn sets in, the minimum temperatures can dip to -1°C (30°F), creating a crisp atmosphere. Expect about 62 mm (2.5 in) of rainfall over 11 days, contributing to the region's lush landscapes. The humidity remains high at 90%, often giving the air a refreshing yet cool feel, making September a transitional month filled with the vibrant colors of fall.
In September, Lahti, Finland experiences a noticeable transition as summer wanes and autumn approaches. While the average temperature settles at a cool 11°C (52°F), the month opens with relatively mild days, where highs can reach up to 23°C (73°F), offering a last taste of warmth before the chill sets in. The nights, however, can drop to around -1°C (30°F), hinting at the cooler months to follow. This month serves as a bridge, blending the lingering warmth of summer with the crispness of fall, making it a beautiful time to witness the changing foliage and enjoy outdoor activities amidst the fluctuating temperatures.
In September, Lahti, Finland, experiences a notable shift in precipitation patterns as summer gives way to autumn. With an average rainfall of 62 mm (2.5 in), September showcases a decrease compared to the preceding months of July and August, which recorded 77 mm (3.0 in) and 80 mm (3.2 in) respectively. Despite the drop in rainfall, the number of precipitation days remains steady at 11 days, indicating a consistent rhythm of light showers that nurture the vibrant landscapes transitioning into fall. This dynamic marks the onset of cooler weather, while still providing ample moisture to prepare the region for the upcoming shift towards the snowy months ahead.
September in Lahti, Finland, sees a notable increase in humidity, settling at a comfortable 90%. This transition marks a return to more moisture-laden air after the relatively drier summer months, where June and July recorded humidity levels of 74% and 80%, respectively. As autumn approaches, humidity levels gradually rise, echoing the trend seen in previous years, where the onset of fall brings a shift from the drier conditions of late spring and summer. This annual pattern hints at the region's characteristic climate, where the closer months of October and November also maintain high humidity, echoing last month's transition. Thus, September serves as a pivotal month, bridging the drier warmth of summer and the moist chill of fall.
In September, Lahti experiences a moderate UV Index of 3, indicating that while sun exposure is generally safe, some precautions are still advisable. With a burn time of about 30 minutes, it's essential for residents and visitors alike to enjoy the outdoors responsibly as the summer sun begins to wane. This month's UV levels reflect a shift from the higher peaks seen in the summer, signaling the transition into autumn. Keeping an eye on UV fluctuations throughout the year can help you make informed decisions about sun safety, whether you're basking in the lingering warmth or embarking on outdoor adventures. For more detailed insights into the UV Index in Lahti, you can visit Lahti UV Index.
UV Risk Categories
September in Lahti, Finland, offers a delightful continuation of summer's embrace, boasting 257 hours of sunshine. As the days grow shorter, this month sees a clear contrast to January’s meager 44 hours, reflecting a vibrant progression through the year. Following the impressively bright summer months of June and July, where sunshine peaked at 475 and 467 hours respectively, September serves as a gentle transition into autumn. Although the sun begins to retreat, the backdrop of golden leaves and cool breezes makes the remaining warmth all the more precious. This gradual decline in sunlight from the peak summer months to the cozy fall is a reminder of nature's rhythmic cycle and the importance of savoring every warm moment as the seasons shift.
In Lahti, Finland, the likelihood of sunny weather experiences a notable ebb and flow throughout the year. Starting from a mere 3% in January, the sun begins to make more frequent appearances as spring approaches, peaking at 56% in the warm summer months of July. However, as summer begins to wane, September sees a decline, with only a 22% chance of sunny days. This trend reflects the transition from the vibrant warmth of summer to the cooler, cloudier fall months ahead. As such, while September may not boast the same sunshine as its summer predecessors, it still offers a glimpse of pleasant weather as the landscape prepares for autumn.
As September unfolds in Lahti, Finland, daylight begins to wane, with the city enjoying about 12 hours of sunlight each day. This gradual shift marks a transition from the vibrant warmth of summer, where daylight peaked at a glorious 19 hours in June, to the shorter days that herald the approach of winter. The month is characterized by a noticeable decrease in daylight compared to August's 15 hours, yet it remains a time of beauty as the rich hues of autumn start to paint the landscape. As the year progresses, the trend of diminishing sunlight continues, reminding residents and visitors alike of the seasonal cycles that shape life in this northern city.
As September unfolds in Lahti, Finland, residents experience a gentle breeze with an average wind speed of 3.3 m/s (7 mph), comparable to the earlier summer months. After a calm spell in June and July, where winds dipped to their lowest, nature seems to rally again in August with a brisker pace of 3.6 m/s (8 mph), hinting at the approach of autumn. This slight revitalization continues into September, creating a refreshing atmosphere that invites outdoor strolls amidst colorful foliage. As October approaches, the winds are expected to pick up further to 4.1 m/s (9 mph), marking a shift towards the gustier months ahead, where the dance of leaves becomes a lively spectacle against the backdrop of Lahti’s scenic beauty.
Weather in Lahti varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Lahti, focusing on differences in temperature, rainfall, humidity, and UV levels.
In September, temperatures are relatively mild, ranging from a minimum of -1°C (30°F) to a comfortable average of 11°C (52°F), and peaking at a maximum of 23°C (73°F). The month experiences 62 mm (2.5 in) of precipitation over 11 days, coupled with high humidity levels around 90%. In stark contrast, January brings much colder conditions, with temperatures plummeting to a minimum of -25°C (-13°F) and an average of -4°C (25°F), while reaching a maximum of only 7°C (46°F). Although January has slightly less precipitation at 49 mm (1.9 in), it maintains high humidity at 98%, resulting in a more frigid and damp environment. For more detailed information about January weather, you can visit Lahti weather in January.
September and February exhibit stark contrasts in weather. September offers milder conditions, with temperatures ranging from a chilly 1°C (30°F) to a pleasant peak of 23°C (73°F), accompanied by relatively high humidity at 90% and precipitation levels of 62 mm over 11 days. In contrast, February brings much harsher temperatures, plunging as low as -28°C (-17°F) and averaging around -5°C (24°F), with a maximum of just 7°C (46°F). Precipitation is lighter in February at 45 mm, yet the humidity remains high at 96%, creating a damp cold. For more details on February weather, you can visit Lahti weather in February.
When comparing the weather in September to that of March, notable differences emerge. September typically features a milder climate with temperatures ranging from a minimum of -1°C (30°F) to a maximum of 23°C (73°F), averaging around 11°C (52°F), and experiences about 62 mm (2.5 in) of precipitation over 11 days, accompanied by relatively high humidity levels at 90%.
In contrast, March presents a much colder atmosphere, with temperatures plummeting to a minimum of -25°C (-13°F) and peaking at just 11°C (52°F), yielding an average temperature of -2°C (29°F). Although the precipitation is slightly lower at 45 mm (1.8 in) for the same number of days, the humidity is marginally higher at 93%. For a closer look at specific weather conditions, you can check Lahti weather in March.
When comparing the weather in September and April, notable differences in temperature and precipitation emerge. September typically enjoys milder conditions with an average temperature of 11°C (52°F), reaching highs of 23°C (73°F), while April remains cooler with an average of just 3°C (38°F) and maximums of 20°C (69°F). In terms of precipitation, September sees a bit more rain with 62 mm (2.5 in) over 11 days compared to April's 48 mm (1.9 in) also spread across 11 days. However, humidity levels are relatively similar, with September at 90% and April at 87%. For more detailed insights into April weather, check out Lahti weather in April.
In comparing the weather of September and May, we can see notable differences in temperature and humidity. September boasts a mild average temperature of 11°C (52°F), peaking at a maximum of 23°C (73°F), whereas May presents a slightly cooler average of 10°C (50°F) with a higher maximum of 28°C (83°F). Precipitation levels are similar, with September receiving 62 mm (2.5 in) over 11 days and May having slightly less at 54 mm (2.1 in) across 10 days. Additionally, the humidity in September is quite high at 90%, compared to a more comfortable 75% in May. For more details, you can visit Lahti weather in May.
September weather in Lahti is generally cooler than June, with temperatures ranging from a minimum of -1°C (30°F) to an average of 11°C (52°F) and a maximum of 23°C (73°F). In contrast, June enjoys milder conditions, with temperatures starting at a minimum of 2°C (35°F) and peaking at an average of 16°C (61°F) and a high of 31°C (87°F). Both months receive similar amounts of precipitation, around 62-63 mm (2.5 in), over approximately 11 days; however, September experiences much higher humidity at 90%, compared to June’s 74%. For more information about the weather during June, you can visit Lahti weather in June.
In comparing the weather between September and July, it's clear that July is significantly warmer, with average temperatures reaching 17°C (64°F) and maximums peaking at 30°C (87°F), compared to September's cooler average of 11°C (52°F) and maximum of 23°C (73°F). July also sees higher minimum temperatures, starting at 7°C (45°F), while September can experience temperatures dropping to -1°C (30°F). Both months experience considerable precipitation, with July receiving 77 mm (3.0 in) over 12 days and September receiving 62 mm (2.5 in) over 11 days. Humidity remains higher in September at 90%, compared to July's 80%. For a more detailed look at July weather in Lahti, you can visit Lahti weather in July.
In comparison to August, September experiences significantly cooler temperatures, with a minimum of -1°C (30°F) and an average of 11°C (52°F), dropping from August's minimum of 6°C (43°F) and average of 16°C (61°F). The maximum temperature in September reaches 23°C (73°F), well below August's high of 31°C (87°F). Additionally, while September sees slightly less precipitation at 62 mm (2.5 in) over 11 days, August has a total of 80 mm (3.2 in) across 13 days. The humidity remains relatively high in both months, at 90% in September compared to 85% in August. For a more detailed look at August weather, you can check Lahti weather in August.
In comparing the weather between September and October, September generally offers milder temperatures with a minimum of -1°C (30°F) and an average of 11°C (52°F), peaking at a comfortable 23°C (73°F). The month experiences 62 mm (2.5 in) of precipitation over 11 days, accompanied by a humidity level of 90%. In contrast, October sees a notable drop in temperatures, with a minimum of -5°C (23°F) and an average of 6°C (43°F), while the maximum reaches 18°C (64°F). The precipitation also increases to 78 mm (3.1 in) over 15 days, and humidity rises slightly to 94%. For more detailed information, check out Lahti weather in October.
In September, the weather is generally milder, with average temperatures ranging from a minimum of -1°C (30°F) to a maximum of 23°C (73°F), and an average of 11°C (52°F). The month experiences about 62 mm (2.5 in) of precipitation over 11 days, coupled with a humidity level of 90%. In contrast, November ushers in colder conditions, with temperatures dropping significantly, ranging from a minimum of -10°C (14°F) to a maximum of 12°C (53°F), averaging only 2°C (36°F). Although November sees a slightly lower precipitation total of 54 mm (2.1 in) over the same number of days, the humidity rises to 94%, creating a chillier atmosphere. For a detailed look at November weather, you can visit Lahti weather in November.
In September, the weather in Lahti is generally mild, with temperatures ranging from a chilly minimum of -1°C (30°F) to a comfortable maximum of 23°C (73°F), and an average of 11°C (52°F). The month experiences a significant amount of rainfall, averaging 62 mm (2.5 in) over 11 days, with a humidity level of 90%.
In contrast, December brings much colder conditions, with temperatures dropping to a minimum of -20°C (-4°F) and a maximum of only 5°C (42°F), leading to an average temperature of -2°C (28°F). This month sees slightly higher precipitation levels at 71 mm (2.8 in) across 16 days, coupled with increased humidity at 96%. For more detailed information, you can check Lahti weather in December.
As September unfolds in Lahti, the weather exhibits a distinct transition from summer warmth to the crisp embrace of autumn. The maximum temperatures start to cool, bringing a refreshing change that contrasts sharply with the warmer months. Alongside this, increased precipitation with a higher frequency of rainy days adds a touch of gray to the landscape, while humidity lingers at a notable level. This month serves as a bridge, where the remnants of summer gradually give way to the colder days ahead. For those curious about the broader patterns shaping Lahti's weather, explore more at Lahti Climate.