Last updated: August 21, 2025
In September, Naantali experiences a delightful transition into autumn, characterized by a maximum temperature reaching 23°C (73°F) and an average of 12°C (54°F). The month can be surprisingly brisk, with lows dipping to -1°C (31°F). Rain is a constant companion, with a total precipitation of 72 mm (2.8 in) spread over approximately 12 days, fostering a lush landscape. Coupled with an average humidity of 86%, the air feels notably crisp and refreshing, making it an ideal time for enjoying the beautiful autumn scenery.
In September, Naantali, Finland, begins to transition from the warmth of summer to the crispness of autumn. Temperatures range from a cool -1°C (31°F) at night to a pleasant 23°C (73°F) during the day, highlighting the lingering warmth before the chill sets in. The average temperature of 12°C (54°F) signals a shift, as the days shorten and nature prepares for the oncoming winter. Compared to the preceding months, September marks a distinct decline in warmth, yet still offers beautiful days that invite residents and visitors alike to enjoy the picturesque scenery of the region. As the month progresses, one can expect a more pronounced drop in temperatures, foreshadowing the colder days ahead.
September in Naantali, Finland, brings a moderate precipitation amount of 72 mm (2.8 in) over approximately 12 days of rain. This marks a slight decrease from the wetter months of August and July, which saw 87 mm (3.4 in) and 75 mm (3.0 in), respectively. The transition into autumn is evident, as September's rainfall prepares the landscape for the approaching chill of October, which typically sees a rise in precipitation again, reaching 86 mm (3.4 in). While the total accumulation in September is significant, the variance in rainy days hints at a shift towards more sporadic weather patterns, making it a month of both transition and anticipation in Naantali's climate cycle.
In Naantali, Finland, September ushers in a notable humidity level of 86%, a slight increase from August's 79%. This month serves as a transition from the summer warmth, as the humidity begins to rise again, following a gradual decline during the late spring and summer months. From a lofty 92% in January to a low of 77% in May, humidity levels show a distinctive pattern of fluctuation throughout the year. As autumn approaches, humidity levels creep back up, signaling the transition into cooler months. October and November see even higher percentages, reaching 90% and 91%, respectively, suggesting that Naantali experiences a moist climate as the seasons change. This trend underscores the region's damp maritime influences, making September a pivotal month in the shift toward autumn's characteristic weather.
As September unfolds in Naantali, Finland, the UV Index registers at 4, indicating a moderate level of sun exposure. This marks a gentle transition from the more intense summer months, where July and June peaked at a high index of 7. As the days shorten and temperatures begin to cool, sun-seekers in September can enjoy about 30 minutes of safe sun exposure before risking burns. It’s a great time to soak up the last rays of sunlight while being mindful of your skin, especially after the moderate readings of May and August. For details on sun safety and daily updates, check out Naantali UV Index.
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As summer gives way to autumn, September in Naantali reveals a charming shift in sunlight, basking in 315 hours of radiant illumination. This marks a graceful decline from the sun-drenched heights of July and June, where residents enjoyed nearly 500 hours of sunny bliss. The month serves as a gentle transition, bridging the warmth of summer and the crispness of fall, while still offering significantly more sunshine than the chilly depths of winter. Compared to the preceding spring months, September’s hours of sunshine reflect a decreasing trend, yet still provide plenty of opportunities to enjoy the picturesque views. As the days shorten and the golden leaves begin to fall, the sunlight’s softer embrace in September invites both locals and visitors to savor the fleeting beauty of the season.
In Naantali, Finland, the likelihood of enjoying sunny weather reaches a modest 32% in September. This marks a slight decline from the previous summer months, which enjoy their peak sunshine, with July and June showcasing the highest probabilities at 57% and 56%, respectively. As the days begin to shorten and autumn approaches, the chances of sunny spells diminish, dipping further into the fall months, where October brings just 18% sunshine likelihood. Interestingly, while September features fewer sunny days compared to summer, it still offers a notable chance for pleasant weather, making it a charming time to explore this coastal gem before the chill of winter sets in.
As summer gives way to autumn in Naantali, Finland, September experiences a noticeable transition in daylight hours. Following the long, sun-soaked days of June and July, which boast a remarkable 18 hours of daylight, the light begins to wane, with September offering a more moderate 12 hours. This gradual decrease reflects the shift into the fall season, where daylight steadily diminishes as the year progresses towards winter. In comparison to August’s 15 hours, September marks a palpable retreat from summer’s peak brightness, setting the stage for the cooler months ahead. As daylight dances between warmth and impending chill, September serves as a gentle reminder of nature’s cyclical rhythm just before evening shadows lengthen in October.
In September, Naantali, Finland experiences a pleasant average wind speed of 4.1 m/s (9 mph), consistent with the breezy conditions of late summer. This month reflects a slight uptick compared to the calmer days of summer, where June recorded just 3.3 m/s (7 mph) and July a modest 3.5 m/s (8 mph). As autumn approaches, the wind speeds begin to escalate, hinting at the upcoming change in season, with October peaking at 5.3 m/s (12 mph). Interestingly, September marks a transition point not only in wind speed but also in atmosphere, as the breeziness complements the stunning autumn hues, creating an inviting and dynamic outdoor experience for both locals and visitors.
Weather in Naantali varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Naantali, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present stark contrasts in weather conditions. September enjoys a milder climate with average temperatures around 12°C (54°F), reaching up to 23°C (73°F) at times, while experiencing 72 mm (2.8 in) of precipitation over approximately 12 days. In contrast, January is characterized by frigid temperatures, with averages plunging to -2°C (29°F) and maximums around 8°C (47°F). This winter month sees less precipitation at 48 mm (1.9 in) but has higher humidity at 92%, coupled with a notable drop to a chilling minimum of -21°C (-6°F). For a detailed look at January weather, you can visit Naantali weather in January.
When comparing the weather in September and February, a dramatic contrast emerges. September brings milder temperatures, ranging from a minimum of -1°C (31°F) to a maximum of 23°C (73°F), averaging at a comfortable 12°C (54°F). This month also sees higher precipitation, with 72 mm (2.8 in) over about 12 days, coupled with humidity levels at 86%. In stark contrast, February is characterized by much colder conditions, with temperatures plummeting to a minimum of -20°C (-4°F) and peaking at just 7°C (44°F), averaging -3°C (27°F). Precipitation is less frequent, totaling 42 mm (1.7 in) across 8 days, yet the humidity remains high at 90%. For a detailed look at February weather, visit Naantali weather in February.
Comparing the weather in September and March reveals notable contrasts. In September, temperatures range from a chilly minimum of -1°C (31°F) to a comfortable average of 12°C (54°F) and a maximum of 23°C (73°F), with total precipitation of 72 mm (2.8 in) over approximately 12 days and a humidity level of 86%. In contrast, March experiences much colder conditions, with temperatures ranging from a frigid minimum of -23°C (-9°F) to an average of 0°C (32°F) and a maximum of 11°C (52°F). March sees less precipitation at 44 mm (1.7 in) over about 9 days, combined with a slightly higher humidity of 89%. For more specific insights on March weather, check out Naantali weather in March.
When comparing the weather in September and April, notable differences emerge. September boasts a milder climate with average temperatures ranging from a minimum of -1°C (31°F) to a maximum of 23°C (73°F), while April is chillier, with temperatures varying from -9°C (16°F) to a peak of 21°C (70°F). Despite September's warmer average, it experiences more precipitation, totaling 72 mm (2.8 in) across 12 days, compared to April's 32 mm (1.3 in) over 9 days. Both months have similar humidity levels, with September at 86% and April slightly lower at 85%. For more insights, check out Naantali weather in April.
When comparing the weather in September and May, notable differences emerge. September features a milder temperature range, with average highs reaching 23°C (73°F) and lows of 1°C (34°F), while May records slightly cooler temperatures, with an average maximum of 26°C (79°F) and minimums dropping to -4°C (26°F). The humidity is higher in September at 86%, contributing to a more humid feel compared to May's 77%. Precipitation is also more frequent in September, with 72 mm (2.8 in) falling over 12 days, whereas May sees less rain, totaling 44 mm (1.7 in) over just 9 days. For a detailed look, you can check out Naantali weather in May.
September and June showcase distinct differences in weather patterns. September tends to be cooler, with temperatures ranging from a minimum of -1°C (31°F) to a maximum of 23°C (73°F) and an average of 12°C (54°F). It also experiences more precipitation, totaling 72 mm (2.8 in) over 12 days, coupled with higher humidity at 86%. In contrast, June benefits from milder temperatures, where the minimum is 3°C (38°F) and can go up to 28°C (83°F), averaging 16°C (61°F). Precipitation in June is less frequent and lighter, with 43 mm (1.7 in) over 7 days and lower humidity at 78%. For more details on June weather, you can check Naantali weather in June.
When comparing the weather between September and July, notable differences emerge. July typically features warmer temperatures, with an average of 18°C (64°F) and maximum highs reaching 31°C (89°F), while September sees cooler averages of 12°C (54°F) and maximums of 23°C (73°F). Additionally, July has fewer precipitation days (11) compared to September's 12 days, though the rainfall amounts are quite similar, with July receiving 75 mm (3.0 in) and September at 72 mm (2.8 in). The humidity also varies, as September experiences higher humidity levels at 86%, compared to July's 78%. For a detailed overview of July's weather, you can check Naantali weather in July.
In comparing the weather between August and September, it's clear that September experiences cooler temperatures, with a minimum of -1°C (31°F) and an average of 12°C (54°F), compared to August's milder range of 6°C (43°F) minimum and an average of 17°C (62°F). August boasts higher maximum temperatures, reaching up to 28°C (83°F), while September only peaks at 23°C (73°F). Precipitation levels are relatively similar, with September receiving 72 mm (2.8 in) over 12 days and August accumulating 87 mm (3.4 in) over 14 days. Additionally, September's humidity is slightly higher at 86%, compared to August's 79%. For more detailed weather information, check out Naantali weather in August.
September and October present distinct shifts in weather patterns. In September, temperatures range from a cool -1°C (31°F) at night to a comfortable high of 23°C (73°F) during the day, with an average of 12°C (54°F). This month witnesses 72 mm (2.8 in) of precipitation over about 12 days, with humidity levels around 86%. In contrast, October sees a further drop in temperatures, with nighttime lows of -5°C (23°F) and daytime highs peaking at 17°C (62°F), averaging at 7°C (46°F). Precipitation increases slightly to 86 mm (3.4 in), spread across 17 days, and humidity also rises to 90%. This transition highlights a cooling climate as fall deepens. For more details, visit Naantali weather in October.
September typically offers a milder climate compared to November, with average temperatures ranging from a minimum of -1°C (31°F) to a maximum of 23°C (73°F). In contrast, November sees lower temperatures, with averages between -8°C (17°F) and 13°C (56°F). Although both months experience similar levels of precipitation—72 mm (2.8 in) in September and 59 mm (2.3 in) in November—November's humidity level is slightly higher at 91% compared to September's 86%. For a more detailed look at what to expect, you can check out Naantali weather in November.
September and December present strikingly different weather patterns. In September, temperatures range from a mild -1°C (31°F) at night to a comfortable 23°C (73°F) during the day, with an average temperature of 12°C (54°F). This month sees about 72 mm (2.8 in) of precipitation over approximately 12 days, accompanied by relatively high humidity at 86%. In contrast, December experiences much colder temperatures, with nighttime lows plummeting to -18°C (-1°F) and daytime highs only reaching 7°C (45°F), resulting in an average temperature of 0°C (32°F). Precipitation increases slightly to 79 mm (3.1 in) over 15 days, and humidity rises to 89%. For those interested in more specifics, check out Naantali weather in December.
As September unfolds in Naantali, the weather showcases a striking transition, marked by a notable decrease in temperature compared to the summer months. With a maximum of 23°C and an average hovering around 12°C, this month ushers in cooler, crisp air, making it a refreshing change from the warmth of earlier in the season. Rainfall becomes more frequent, with 12 days of precipitation adding to the overall 72 mm of rain throughout the month, contributing to the lushness of the landscape. The high humidity of 86% further emphasizes the shift towards autumn, creating a unique ambiance that is both invigorating and serene. For a deeper understanding of Naantali's climate patterns, explore Naantali Climate.