Last updated: August 21, 2025
In Koshima, Japan, September reveals a tropical climate with maximum temperatures reaching 29°C (84°F) and an average of 27°C (80°F), providing warm conditions ideal for outdoor activities. However, visitors should be prepared for the high humidity level of 80%, which can make the heat feel more intense. With a substantial precipitation amount of 256 mm (10.1 in) over approximately 20 rainy days, sudden showers are common, urging travelers to keep an umbrella handy. Despite the rain, the beauty of Koshima in September is vivid and lush, making it a captivating time to explore this coastal paradise.
September in Koshima, Japan, marks a gentle transition from the sweltering summer to the more temperate autumn. With minimum temperatures around 22°C (72°F) and an average rising to 27°C (80°F), the weather remains pleasantly warm, peaking at a comfortable 29°C (84°F). This trend of declining temperatures continues from the scorching heights of July and August, making September an ideal time for outdoor activities and exploring the lush landscapes. As summer's heat mellows, visitors can enjoy balmy days and refreshing evenings, setting the perfect stage for a variety of seasonal festivities that celebrate the beauty of the changing environment.
In September, Koshima, Japan, experiences a notable shift in precipitation, receiving 256 mm (10.1 in) of rain over 20 days. This month typically marks a transition, as the region moves from the humid conditions of summer into the milder autumn season. September’s rainfall is substantial, following the peaks of June's 491 mm (19.3 in) and July's 281 mm (11.0 in), showcasing a significant decrease yet remaining higher than many other months. The increased number of rainy days indicates a persistent drizzle, creating a lush environment that heralds the vibrant colors of autumn to come. As the summer heat wanes, Koshima's September precipitation not only sustains the local ecosystem but also sets the stage for the crisp, refreshing weather that lies ahead.
In September, Koshima experiences a notable shift in humidity, with levels reaching 80%. This marks a slight decrease from the peak humidity of 90% seen in July but is still significantly higher than the winter months. The transition from summer to autumn brings a gradual decline in humidity, as evidenced by the steady drop from the summer highs of August and July. Overall, September's humidity reflects a prevailing trend of high moisture levels that dominate the warmer months, creating a lush and vibrant atmosphere in the region as it prepares for the cooler days ahead.
September in Koshima, Japan, sees a UV Index of 11, falling into the extreme exposure category. As summer gives way to autumn, the UV levels remain notably high, with a burn time of just 10 minutes for unprotected skin. This trend highlights the consistent intensity of UV radiation experienced from April through September, where figures peak in the hotter months of July and August at 13. As the weather transitions into October, there's a noticeable drop to an index of 8, signaling residents and visitors alike to remain vigilant about sun protection during this late summer period. For more detailed insights, check the Koshima UV Index.
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As September arrives in Koshima, Japan, the sunshine continues to grace the region with a generous 284 hours of daylight, marking a slight dip from the peak summer months of July and August but still shining brightly compared to the colder seasons ahead. The trend reveals a remarkable increase in sunshine hours from the beginning of the year, where January started with just 164 hours. As spring transitioned into summer, sunshine hours climbed steadily, reaching a high of 319 hours in August. This gradual ascent culminates in September's robust total, which not only outshines the earlier months like June but also hints at the fading warmth as the days grow shorter. With October's forecast promising 266 hours of sunshine, Koshima's September serves as a delightful reminder of summer's lingering embrace before autumn begins to settle in.
In September, Koshima, Japan, welcomes a notable increase in sunny weather, boasting a 46% chance of sunshine. This uptick marks a significant rise compared to the summer months, where the chances lingered around 26% to 38%. As autumn approaches, the city transitions from the humid heat of summer to clearer skies, providing a perfect backdrop for outdoor activities. Interestingly, September also sets the stage for a gradual improvement in weather conditions leading into October, which has the highest likelihood of sun at 53%. This trend signals a delightful shift for residents and visitors alike, who can enjoy the beautiful early autumn landscapes bathed in sunlight.
As September arrives in Koshima, Japan, daylight begins to gently wane, offering about 12 hours of sunlight each day. This transition reflects a broader trend observed throughout the year, where daylight durations peak in the vibrant summer months of June at 14 hours before gradually declining in the fall. The month of September stands as a delicate balance, bridging the longer days of summer and the shorter days that follow, with October and November both offering just 11 hours and 10 hours of daylight, respectively. This cyclical rhythm of light and darkness invites a reflective shift in nature, as the lush greens of summer prepare to embrace the cooler tones of autumn.
As summer gracefully transitions into autumn, September in Koshima, Japan, brings a noticeable softening in the winds, with average speeds dipping to 5.8 m/s (13 mph). This marks the calmest month of the year, a stark contrast to the brisker breezes prevalent in the earlier months. Following a peak in wind speeds during the colder winter months, where figures hover around 8 m/s, the shift to September showcases a trend of decreasing wind intensity that lasts through mid-year. While the gentle September winds may whisper of change, they set the stage for a gradual return to stronger gusts in the approaching fall, maintaining Koshima’s unique rhythm throughout the seasons.
Weather in Koshima varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Koshima, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present contrasting weather patterns, with September characterized by warm temperatures ranging from a minimum of 22°C (72°F) to a maximum of 29°C (84°F), along with high humidity levels of 80%. This month also sees significant rainfall, averaging 256 mm (10.1 in) over about 20 days. In stark contrast, January experiences cooler temperatures, with a minimum of 6°C (44°F) and an average of 14°C (57°F), peaking at 21°C (70°F). Additionally, January has less precipitation, totaling 108 mm (4.2 in) over approximately 12 days, and a lower humidity of 72%. For a more detailed look at January weather in Koshima, you can visit Koshima weather in January.
September weather is marked by warm temperatures, with a minimum of 22°C (72°F) and an average around 27°C (80°F), peaking at 29°C (84°F). The month also experiences significant rainfall, totaling 256 mm (10.1 in) over 20 days, coupled with high humidity levels at 80%. In contrast, February brings a much cooler climate, with temperatures dropping to a minimum of 7°C (44°F) and averaging 14°C (57°F), reaching a maximum of 21°C (70°F). Rainfall is lower at 157 mm (6.2 in), spread over 16 days, and the humidity is relatively moderate at 68%. For a more detailed look at February weather patterns, visit Koshima weather in February.
In September, the weather tends to be much warmer and more humid, with average temperatures ranging from 22°C (72°F) to a high of 29°C (84°F). This month also experiences significant rainfall, totaling 256 mm (10.1 in) over approximately 20 days, contributing to a high humidity level of 80%. In contrast, March offers cooler temperatures, with a minimum of 10°C (51°F) and a maximum of 22°C (72°F) and an average of 16°C (62°F). While it is also a rainy month, the total precipitation in March is slightly lower at 213 mm (8.4 in) spread over about 16 days, and the humidity is less intense at 72%. For more specific details on March weather, you can visit Koshima weather in March.
In comparing September and April weather, September emerges as significantly warmer, with average temperatures reaching 27°C (80°F) compared to April's cooler average of 19°C (66°F). The maximum temperatures in September peak at 29°C (84°F), while April sees a maximum of only 24°C (75°F). Additionally, September is marked by higher precipitation, with 256 mm (10.1 in) falling over 20 days, contrasted with April’s 186 mm (7.3 in) over just 12 days. Despite the slight difference in humidity, remaining at about 80% in September and 79% in April, the overall climate in September tends to feel much more oppressive due to both the heat and increased rainfall. For a closer look at April's weather specifics, you can visit Koshima weather in April.
When comparing the weather between September and May, September tends to be warmer, with average temperatures reaching 27°C (80°F) and maximums of 29°C (84°F), compared to May's average of 22°C (71°F) and maximum of 26°C (78°F). However, both months experience significant rainfall, with September receiving 256 mm (10.1 in) over 20 days, slightly less than May, which sees 273 mm (10.7 in) but with fewer rainy days, totaling 13. Humidity levels in September average around 80%, while May is slightly higher at 83%. For those looking to explore the weather specifics in May, you can find more information here: Koshima weather in May.
In comparing the weather between September and June, we notice notable differences in both temperature and precipitation. September tends to be warmer, with average temperatures reaching 27°C (80°F) compared to June's average of 24°C (76°F). However, June experiences significantly higher precipitation, accumulating 491 mm (19.3 in) over 19 days, which is almost double the 256 mm (10.1 in) in September, despite both months featuring a similar number of rainy days. Additionally, June has slightly higher humidity levels at 86%, compared to September's 80%. For more detailed information on weather patterns, you can explore Koshima weather in June.
In comparison, the weather in September is slightly cooler than in July, with average temperatures hovering around 27°C (80°F) in both months, but September features a lower maximum of 29°C (84°F) compared to July's 30°C (86°F). Both months experience significant rainfall, with September receiving 256 mm (10.1 in) over 20 days and July slightly higher at 281 mm (11.0 in) over 17 days. Additionally, humidity levels are high in both months, peaking at 90% in July and at 80% in September, making July feel a bit more oppressive. For a more detailed look at July conditions, you can check Koshima weather in July.
In comparing the weather of September to August, we see that September tends to be slightly cooler, with minimum temperatures at 22°C (72°F) compared to August's 24°C (76°F). The average temperature in September is 27°C (80°F), while August averages 28°C (82°F), and September's maximum temperature reaches 29°C (84°F) against August's 30°C (86°F). In terms of precipitation, September is rainier, with 256 mm (10.1 in) over 20 days, compared to August's 214 mm (8.4 in) across 16 days. Additionally, humidity levels are consistently high, peaking at 85% in August and just slightly lower at 80% in September. For a more detailed breakdown, you can check Koshima weather in August.
In September, the weather is typically warmer, with average temperatures reaching around 27°C (80°F) and maximum highs of 29°C (84°F). This month also brings considerable rainfall, totaling 256 mm (10.1 in) over approximately 20 days, paired with high humidity levels of 80%. In contrast, October sees a noticeable drop in temperature, with averages falling to 24°C (75°F) and maximums around 27°C (81°F). Additionally, precipitation decreases significantly to 164 mm (6.4 in) over just 13 days, and humidity slightly lowers to 78%. For more detailed insights on October weather in Koshima, please visit Koshima weather in October.
In September, the weather remains warm and humid, with temperatures averaging around 27°C (80°F) and a notable amount of precipitation at 256 mm (10.1 in) over approximately 20 days. The humidity level is high at 80%, making the air feel quite sultry. In contrast, November brings a significant drop in temperatures, with an average of 20°C (68°F) and cooler minimums of 13°C (56°F). Precipitation decreases to 150 mm (5.9 in) over 13 days, and the humidity is slightly lower at 76%. Thus, while September is characterized by wetter and warmer weather, November transitions into a cooler and drier climate. For more details, you can check Koshima weather in November.
In September, the weather is typically warm and humid, with average temperatures around 27°C (80°F) and a high of 29°C (84°F). This month sees a significant amount of rainfall, totaling 256 mm (10.1 in) over about 20 days, contributing to the humidity levels reaching 80%. In stark contrast, December experiences much cooler temperatures, with an average of 16°C (61°F) and highs reaching 24°C (75°F). The precipitation decreases to 132 mm (5.2 in) over 14 days, resulting in lower humidity at 74%. For more specific information on December weather, you can visit Koshima weather in December.
As September arrives in Koshima, the weather showcases a unique blend of warmth and moisture, setting it apart from the drier summer months. With average temperatures hovering around a comfortable 27°C, the city maintains a pleasant atmosphere, though the humidity can be quite high, reaching 80%. This month also sees a significant increase in rainfall, with precipitation occurring on nearly two-thirds of the days, bringing the total to an impressive 256 mm. This lush, vibrant weather is ideal for experiencing the region's natural beauty, making September a captivating time to visit. For further insights into Koshima's climate patterns, check out Koshima Climate.