Last updated: March 17, 2025
September in Keflavik, Iceland, ushers in a refreshing transition from summer, characterized by cool temperatures and frequent rainfall. With a maximum of 13°C (56°F) and an average of 9°C (48°F), visitors should be prepared for brisk days and chilly nights, dipping to a minimum of 1°C (34°F). The month sees substantial precipitation, accumulating to 171 mm (6.7 in) over approximately 21 days, contributing to an impressive humidity level of 85%. This combination of elements not only enriches the stunning natural landscapes but also invites adventurers and nature lovers to experience the enchanting beauty of Iceland's early autumn.
As September unfolds in Keflavik, Iceland, the temperatures begin to shift noticeably, heralding the arrival of autumn. With minimums averaging around 1°C (34°F) and maximums reaching 13°C (56°F), this month feels significantly milder compared to the chillier grip of winter that follows. The average temperature settles at 9°C (48°F), providing a comfortable transition for visitors keen to explore the enchanting landscapes before the first snows. Compared to August, which enjoys warmer highs of 16°C (62°F), September marks a gentle decline, making it an ideal time for those who appreciate the crisp air and fewer crowds. As daylight hours decrease, the chance to witness the Northern Lights begins to increase, adding a magical allure to the early autumn experience.
September marks a significant shift in Keflavik's weather pattern, with precipitation levels rising dramatically to 171 mm (6.7 in)—the highest of the year. This increase is accompanied by 21 rainy days, making it a notably wet month as autumn approaches. The trend of increasing precipitation becomes evident when comparing it to the summer months, where July and August saw relatively low rainfall of 78 mm (3.1 in) and 89 mm (3.5 in), respectively. As the warm season gives way to fall, residents and visitors in Keflavik can expect not only more consistent rain but also a lush transformation of the landscape, highlighting the beauty and unpredictability of Icelandic weather.
In Keflavik, Iceland, September marks the transition into autumn, bringing with it a humidity level of 85%. This figure is part of a generally high humidity pattern that begins in late spring and peaks in July and August, reaching 87% and 88% respectively. As summer fades, humidity remains relatively stable, only slightly decreasing in September from the summer highs, which reflects the persistent dampness characteristic of Iceland's coastal climate. Interestingly, the humidity during this early autumn month is consistent with the levels seen in May and June, showcasing a continuity in moisture before the onset of colder months. Overall, while September may signal a shift in seasons, its humidity holds firm, ensuring that Keflavik retains its signature refreshing chill.
As summer fades into autumn, September in Keflavik sees a moderate UV Index of 3, indicating a shift from the height of summer’s intensity. During this month, the burn time decreases slightly to 30 minutes, suggesting a need for casual sun protection outdoors. Following the peak UV months of June and July, which both registered a high index of 6, this transition demonstrates a gradual decline in sun exposure risk. Nonetheless, September's UV levels still require awareness, particularly for those planning outdoor activities. Enjoy the crisp Icelandic air while staying mindful of the sun—more insights can be found at Keflavik UV Index.
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As September arrives in Keflavik, Iceland, the days gradually transition into autumn, bringing a delightful 207 hours of sunshine—a significant drop compared to the sun-soaked summer months but markedly brighter than the bleak winter ahead. This month experiences a gentle decline in sunlight, following the vibrant glow of 344 hours in May and 312 hours in July, with each passing month showcasing a clear trend of diminishing daylight as Iceland bids farewell to summer. While September marks a shift, it still offers a taste of brightness, reminding visitors of the lingering warmth that softens the onset of the darker days to come.
In September, the likelihood of sunny weather in Keflavik, Iceland, tends to hover around 15%, reflecting a trend of transitional weather as summer gives way to autumn. Notably, this figure is relatively consistent with the preceding months of July and August, which see even lower chances of sunshine at 13% and 12%, respectively. In contrast, the earlier part of the year showcases more variability, with May boasting a much higher 49% chance of sunny days. As we move into October, the likelihood improves slightly to 26%, hinting at a brief resurgence of sunny spells, but overall, September remains a month where sunshine is more of a rare gem than a frequent visitor. Thus, for those planning a trip, be prepared for the possibility of overcast skies, with any rays of sunshine being a delightful surprise.
As September arrives in Keflavik, Iceland, the transition from summer to autumn becomes evident with a daylight duration of 12 hours. Following the peak of 20 hours in June, the days gradually shorten, offering a gentle reminder of the shifting seasons. While still enjoying ample sunlight compared to the winter months, September marks a significant decrease from the lush daylight of summer. This month bridges the vibrant glow of late summer, where August boasts 16 hours of daylight, and the impending gloom of October, which plunges to just 9 hours. Overall, September serves as a beautiful interlude, capturing the essence of change as daylight wanes, inviting a time of reflection and appreciation for the stunning landscapes bathed in soft autumn light.
As summer transitions to autumn in Keflavik, Iceland, September brings a refreshing shift in the air, with an average wind speed of 7.2 m/s (16 mph). This gusty resurgence is reminiscent of the blustery conditions of earlier months, as it mirrors the wind speed of January, February, and March, which also hover around 7.2 m/s. However, after enjoying the relatively calm breezes of late spring and summer, where winds dipped to a gentle 4.8 m/s, the return to stronger gusts signals a change in the season. Interestingly, while October and November maintain similar wind speeds to September, the overall trend shows a gradual windier climate as the year progresses, reminding all that in this stunning landscape, nature is always in motion.
The weather in Keflavik 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 Keflavik and find detailed weather information for every month.
In September, temperatures gradually transition from a mild average of 9°C (48°F) with a minimum of 1°C (34°F) to a maximum of 13°C (56°F), while the weather is quite humid at 85%. The month also sees a significant amount of precipitation, with rain falling on about 21 days and totaling 171 mm (6.7 in). In contrast, January presents a much colder climate, with average temperatures dropping to around 2°C (36°F) and a minimum of -6°C (22°F), peaking at a maximum of 9°C (49°F). Precipitation is slightly lower, totaling 117 mm (4.6 in) over 17 days, and humidity dips to 80%. For more detailed insights, check out Keflavik weather in January.
In September, temperatures range from a minimum of 1°C (34°F) to a maximum of 13°C (56°F), with an average of 9°C (48°F), while February experiences colder conditions with temperatures dropping as low as -9°C (16°F) and peaking at 8°C (47°F), averaging around 2°C (36°F). September is notably wetter, receiving 171 mm (6.7 in) of precipitation over 21 days, compared to February's 126 mm (5.0 in) across 19 days. Additionally, humidity levels are higher in September at 85%, compared to 77% in February. For more detailed information, check out Keflavik weather in February.
When comparing the weather in September and March, we see notable differences in temperature and precipitation patterns. September tends to be milder, with average temperatures ranging from a chilly 1°C (34°F) at night to a comfortable 13°C (56°F) during the day, while March experiences colder temperatures, with a minimum of -6°C (21°F) and a maximum of only 8°C (47°F). Despite September's higher average temperature, it receives significantly more precipitation, amounting to 171 mm (6.7 in) over 21 days, compared to March's 110 mm (4.3 in) over 18 days. Additionally, September has a higher humidity level at 85% compared to March's 82%. For those interested in specific weather patterns, you can explore the details further at Keflavik weather in March.
September and April exhibit distinct weather patterns, showcasing the transitional phases of summer to autumn and winter to spring, respectively. In September, temperatures range from a minimum of 1°C (34°F) to a maximum of 13°C (56°F), with an average temperature of 9°C (48°F). The month experiences significant rainfall, with 171 mm (6.7 inches) spread over 21 days and a humidity level of 85%. In contrast, April is a cooler month, featuring temperatures that span from a minimum of -7°C (20°F) to a maximum of 11°C (52°F), averaging at 5°C (41°F). While it receives slightly less precipitation at 133 mm (5.2 inches) over 18 days, the humidity is slightly lower at 80%. For more detailed insights, you can check out this link: Keflavik weather in April.
September and May present a contrast in weather conditions, despite their proximity in the calendar. In September, temperatures range from a chilly 1°C (34°F) at night to a mild maximum of 13°C (56°F) during the day, while May features slightly cooler averages, with temperatures dipping to 0°C (33°F) at night and reaching a maximum of 12°C (54°F). Rainfall is more abundant in September, with 171 mm (6.7 in) of precipitation over 21 days compared to May's 115 mm (4.5 in) over just 16 days. Notably, both months share similar humidity levels at 85%, making the air feel consistently damp. For a closer look at May's weather specifics, you can check Keflavik weather in May.
In comparing the weather of September and June, we find that September tends to be cooler overall, with maximum temperatures reaching only 13°C (56°F) compared to June's maximum of 15°C (60°F). Both months have similar average temperatures of 9°C (48°F) and humidity levels of 85%. However, September experiences significantly more precipitation, with 171 mm (6.7 in) falling over 21 days, while June receives only 87 mm (3.4 in) over 15 days. For those interested in more details about June's weather, you can explore Keflavik weather in June.
In comparing the weather of September and July, we find distinct differences that characterize each month. September experiences cooler temperatures, with a minimum of 1°C (34°F) and an average of 9°C (48°F), whereas July is milder, with temperatures ranging from a minimum of 6°C (43°F) to a maximum of 19°C (66°F). Precipitation also varies significantly; September records 171 mm (6.7 in) over 21 days, indicating a wetter month compared to July, which receives only 78 mm (3.1 in) across 18 days. Additionally, humidity remains relatively high in both months, peaking at 85% in September compared to 87% in July. For more details on July weather in this region, you can refer to Keflavik weather in July.
In comparing the weather of September and August, a noticeable shift towards cooler temperatures is apparent. September experiences a broader range, with minimum temperatures dropping to 1°C (34°F) and a maximum of 13°C (56°F), while August maintains a milder range, with temperatures from a minimum of 7°C (45°F) to a maximum of 16°C (62°F). Additionally, September sees significantly higher precipitation, totaling 171 mm (6.7 in) over 21 days compared to August's 89 mm (3.5 in) over 13 days. This increase in rainfall contributes to September's higher humidity of 85%, slightly lower than August's 88%. For a more detailed view of August's weather, you can check out Keflavik weather in August.
In September, the weather is characterized by slightly milder temperatures, with minimums around 1°C (34°F) and an average of 9°C (48°F), while October sees a dip with minimums reaching -1°C (30°F) and an average of 6°C (44°F). While both months experience high humidity at 85%, September is notably wetter, accumulating 171 mm (6.7 in) of precipitation over 21 days compared to October's 119 mm (4.7 in) over 18 days. As the season transitions, October provides a slight reprieve in terms of rainfall, but the cooler temperatures signal the approach of winter. For a detailed outlook on October conditions, you can visit Keflavik weather in October.
September and November present quite different weather patterns. In September, temperatures range from a minimum of 1°C (34°F) to a maximum of 13°C (56°F), with an average of 9°C (48°F). The month experiences a considerable amount of rainfall, totaling 171 mm (6.7 in) over 21 days, along with high humidity at 85%. In contrast, November sees cooler temperatures, with a range from -4°C (25°F) to 10°C (51°F) and an average of just 4°C (39°F). The precipitation is lower at 119 mm (4.7 in) over 18 days, and humidity drops slightly to 81%. For more detailed insights, you can check out Keflavik weather in November.
In September, temperatures in Keflavik range from a minimum of 1°C (34°F) to a maximum of 13°C (56°F), with an average temperature of 9°C (48°F). The month experiences significant rainfall, totaling 171 mm (6.7 in) over 21 days, and the humidity averages around 85%. In contrast, December sees a drop in temperatures, with a minimum of -6°C (21°F), an average of 2°C (37°F), and a maximum of 9°C (49°F). Precipitation decreases to 119 mm (4.7 in) over 18 days, and humidity is slightly lower at 80%. For a more detailed look at the weather conditions in December, check out Keflavik weather in December.
September in Keflavik marks a significant shift from the warmer summer months as temperatures begin to cool, averaging around 9°C, with minimums dipping as low as 1°C. This month also ushers in increased precipitation, with nearly 21 days of rain contributing to a humdity level of 85%, creating a distinctly wet and brisk atmosphere. While the vibrant colors of autumn start to emerge, the weather remains variable, making it essential for visitors to pack accordingly. For those curious about the year-round climate in this captivating region, detailed insights can be found at Keflavik Climate.