Last updated: August 21, 2025
September in Karatsu, Japan presents a delightful blend of warm temperatures and noticeable humidity. With daily highs reaching a maximum of 32°C (91°F) and an average of 25°C (77°F), the weather remains inviting for outdoor adventures. However, as the month progresses, expect the occasional rainfall, totaling approximately 210 mm (8.3 in) over 16 days, creating a lush environment. The humidity hovers around a muggy 84%, reminding visitors that while soaking up the sun, a light breeze or parasol might enhance their comfort. Overall, September in Karatsu is a captivating time to experience the beauty of Japan, with vibrant landscapes and rich cultural festivals set against a backdrop of changing weather.
In September, Karatsu, Japan experiences a delightful transition as summer begins to fade, bringing with it milder temperatures and a hint of autumn. With minimums around 19°C (66°F) and averages climbing to 25°C (77°F), the weather is pleasantly warm, perfect for outdoor activities and enjoying the natural beauty of the region. The maximum temperature can soar up to 32°C (91°F), creating a lingering warmth reminiscent of summer. This month strikes an ideal balance, making it an inviting time for visitors to explore the vibrant local culture, enjoy seasonal festivities, and appreciate the stunning landscapes without the intense heat of the peak summer months. As September unfolds, the softer climate welcomes both locals and tourists, fostering a sense of connection to the enchanting surroundings.
In September, Karatsu experiences a notable shift in its precipitation patterns, receiving an average of 210 mm (8.3 in) over 16 days. This marks a decrease compared to the summer months, especially from the peak rainfall seen in July with 323 mm. As the season transitions, September's downpours signify the tail end of summer storms, while still providing substantial moisture that contributes to the region's lush landscapes. The rainfall, though less intense than in the previous months, is crucial for replenishing the area's water resources ahead of the drier fall and winter months. Overall, this month’s precipitation highlights a gradual moderation in rainfall, bridging the heavy summer showers and the more temperate conditions that follow.
As the summer heat begins to wane, September in Karatsu, Japan brings a notable dip in humidity, averaging at 84%. This shift marks a transition from the sweltering peak months of July and August, where humidity levels soared to 97% and 94%, respectively. While September's figures still indicate a relatively humid environment, they signal a reprieve from the intense moisture of summer. Following this month, humidity continues its downward trend into October at 79%, suggesting a gradual shift toward the drier and cooler autumn months ahead. Overall, September serves as a pivotal point in Karatsu’s climate, bridging the sultry summer to the more temperate fall season.
In September, Karatsu, Japan experiences an UV Index of 11, maintaining the extreme exposure category seen in the previous summer months. As a result, the recommended burn time remains a brief 10 minutes, reflecting a trend of high solar intensity that persists into early autumn. This pattern highlights the importance of sun protection as summer transitions to fall, with UV levels remaining significant even as temperatures begin to cool. As always, it's wise to stay informed and take precautions during these high UV conditions. For more details, visit Karatsu UV Index.
UV Risk Categories
As summer fades, September in Karatsu, Japan offers a delightful balance of sunshine, boasting 257 hours of radiant daylight. While this marks a drop from the sun-soaked 305 hours of August, it still echoes the vibrant warmth of the previous months. The trend reveals a gradual decline in sunlight as the year progresses, peaking mid-summer before transitioning into a more tempered autumn. This golden month provides a perfect opportunity to soak in the lingering warmth and enjoy the beautiful scenery, making Karatsu an ideal choice for those looking to experience the lingering summer sun before the cool embrace of autumn settles in.
As September rolls into Karatsu, Japan, the likelihood of sunny weather stands at 33%, reflecting a modest improvement compared to the summer months, notably July and August, which experience significantly lower sunshine chances at 21% and 29% respectively. This slight uptick hints at the transition from the hot, humid days of summer to the more temperate conditions of autumn. While September does not boast as high a chance of sun as October’s impressive 60%, it welcomes a balance of pleasant weather, encouraging outdoor activities and exploration of the scenic beauty that Karatsu has to offer. The evolving patterns in this coastal city show that while summer may retreat, the allure of sunny days persists into early autumn.
As the calendar turns to September in Karatsu, Japan, daylight begins to gently wane, offering about 12 hours of sunlight each day. This marks a noticeable shift from the peak summer months of June and July, where daylight stretches to 14 hours, providing ample time for outdoor activities. August sees a slight decrease, and by September, the days continue their graceful descent towards autumn, transitioning toward the shorter days of October and November, which average 11 hours and 10 hours respectively. This seasonal rhythm not only influences the natural landscape but also encourages locals to savor the remaining warmth and daylight before the chill of winter sets in.
As September arrives in Karatsu, Japan, the average wind speed gently rises to 3.6 m/s (8 mph), marking a transition from the calmer breezes of summer. Following a trend of gradually decreasing wind from May’s 3.7 m/s to the low of 2.7 m/s in June, the winds begin to pick up again, foreshadowing the brisker days ahead. This month’s winds are a prelude to the stronger gusts that characterize the autumn months, particularly November, where speeds reach 4.3 m/s (10 mph). September's mild yet refreshing air invites both locals and visitors to embrace the beauty of changing seasons, providing the perfect backdrop for outdoor explorations.
Weather in Karatsu varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Karatsu, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present starkly contrasting weather patterns. In September, temperatures are warm, ranging from a minimum of 19°C (66°F) to a maximum of 32°C (91°F), with an average of 25°C (77°F) and high humidity at 84%. This month sees considerable rainfall, with about 210 mm (8.3 in) spread over 16 days. In sharp contrast, January brings significantly cooler temperatures, with a minimum of -1°C (31°F) and a maximum of 18°C (64°F), averaging around 8°C (46°F). January experiences much less precipitation at 69 mm (2.7 in) over just 9 days, and the humidity is also lower at 73%. For more detailed information, check out Karatsu weather in January.
September and February present contrasting weather experiences. In September, temperatures range from a minimum of 19°C (66°F) to a maximum of 32°C (91°F), with an average of 25°C (77°F). The month is characterized by high humidity at 84% and significant rainfall, accumulating to 210 mm (8.3 in) over 16 days. In contrast, February is much cooler, with temperatures dipping as low as 0°C (31°F) and only reaching up to 19°C (67°F), averaging just 8°C (47°F). Precipitation decreases notably to 84 mm (3.3 in) over 11 days, and humidity is lower at 69%. For more detailed information, you can visit Karatsu weather in February.
September and March showcase a stark contrast in weather conditions. September typically experiences warmer temperatures, ranging from a minimum of 19°C (66°F) to a maximum of 32°C (91°F), with an average of 25°C (77°F). In this month, the region also faces significant rainfall, totaling 210 mm (8.3 in) over about 16 days and high humidity levels at 84%. Conversely, March is much cooler, with temperatures ranging from a low of 5°C (41°F) to a high of 20°C (68°F), averaging only 12°C (53°F). It also sees less precipitation, at 136 mm (5.4 in) over 11 days, and a lower humidity of 71%. For more detailed insights into the climate during this month, you can visit Karatsu weather in March.
September and April present quite contrasting weather conditions. In September, temperatures range from a minimum of 19°C (66°F) to a maximum of 32°C (91°F), with an average of 25°C (77°F). The month is also characterized by high humidity at 84% and significant precipitation, totaling 210 mm (8.3 in) across 16 days. In stark contrast, April features much cooler temperatures, with a minimum of 7°C (45°F) and a maximum of 24°C (75°F), averaging only 15°C (59°F). April experiences less rainfall, accumulating 115 mm (4.5 in) over 9 days, and has a slightly lower humidity level at 79%. For a detailed look at April weather in Karatsu, check out Karatsu weather in April.
In September, the weather is notably warmer than in May, with average temperatures ranging from a minimum of 19°C (66°F) to a maximum of 32°C (91°F), compared to May’s range of 11°C (53°F) to 27°C (80°F). September also experiences higher humidity at 84%, although May has a slightly higher humidity level at 87%. Precipitation is more frequent in September, with 210 mm (8.3 in) falling over 16 days, while May sees 153 mm (6.0 in) across 11 days. For more detailed information, you can explore Karatsu weather in May.
In September, temperatures range from a minimum of 19°C (66°F) to a maximum of 32°C (91°F), offering an average of 25°C (77°F). This month experiences quite a bit of rain, with a total precipitation of 210 mm (8.3 in) spread over 16 days, and humidity levels are notably high at 84%. In contrast, June presents slightly cooler temperatures, with a minimum of 17°C (63°F) and a maximum of 29°C (84°F), averaging 22°C (73°F). Rainfall is also considerable in June, with a total of 191 mm (7.5 in) over 13 days, but humidity is marginally higher at 91%. For a more detailed look at weather patterns, you can refer to Karatsu weather in June.
September weather exhibits slightly cooler temperatures compared to July, with average highs of 32°C (91°F) dropping from July's peak of 33°C (91°F). The minimum temperatures in September are around 19°C (66°F), just a degree lower than July's minimum of 20°C (68°F). However, September experiences more rain, with a total precipitation of 210 mm (8.3 in) over 16 days, while July sees higher precipitation levels of 323 mm (12.7 in) across 18 days, leading to higher humidity levels of 97% in July compared to September's 84%. For more detailed insights into the weather dynamics of July, check out Karatsu weather in July.
In comparing the weather between August and September, we see notable differences in temperature and precipitation. September experiences slightly cooler temperatures, with a minimum of 19°C (66°F) and an average of 25°C (77°F), while August is warmer, showcasing a minimum of 21°C (70°F) and an average of 28°C (83°F). Moreover, September sees a decrease in total precipitation, accumulating 210 mm (8.3 in) over 16 days, compared to August's higher total of 266 mm (10.5 in) over just 13 days. Humidity remains high in both months, but it is marginally lower in September at 84%, compared to August's 94%. For a detailed look at what to expect in August, visit Karatsu weather in August.
September's weather is characterized by warmer temperatures, with average highs reaching 32°C (91°F) and a muggy humidity level of 84%. The month experiences significant rainfall, totaling 210 mm (8.3 in) over 16 days, making it one of the wetter months. In contrast, October brings a notable drop in temperatures, with a maximum of 29°C (84°F) and a more comfortable average of 20°C (69°F). The humidity also decreases slightly to 79%, and rainfall diminishes to 112 mm (4.4 in) over just 10 days. For more details about October weather in Karatsu, you can check Karatsu weather in October.
In September, the weather is notably warmer, with average temperatures ranging from a minimum of 19°C (66°F) to a maximum of 32°C (91°F), creating a warm and humid atmosphere, as reflected in the high humidity of 84%. This month also experiences substantial rainfall, with 210 mm (8.3 in) falling on around 16 days. In contrast, November brings a significant temperature drop, with averages hovering between 7°C (45°F) and a maximum of 23°C (74°F), leading to a cooler and drier climate, as evidenced by only 53 mm (2.1 in) of precipitation over just 7 days. You can find more specific details about November weather here.
September and December present a stark contrast in weather patterns. September enjoys warmer temperatures, with averages around 25°C (77°F) and highs reaching up to 32°C (91°F), while December cools down significantly, with averages dropping to 10°C (50°F) and highs peaking at 21°C (71°F). In terms of precipitation, September is quite wet, experiencing about 210 mm (8.3 in) over 16 days, whereas December sees much less rain, with only 81 mm (3.2 in) over 9 days. Furthermore, the humidity in September is notably higher at 84%, compared to the 72% in December, contributing to a much different feel between the two months. For more detailed information on December weather in Karatsu, visit Karatsu weather in December.
September in Karatsu marks a transition, blending the warmth of summer with the onset of autumn. While temperatures hover comfortably around 25°C (77°F), the month witnesses increased rainfall, with 16 days of precipitation contributing to a total of 210 mm (8.3 in). The humidity during this time is notably high at 84%, creating a muggy atmosphere that distinguishes September from the typically drier summer months. As the landscape shifts from vibrant greens to the early hues of fall, it's an ideal time to experience the region's natural beauty. For more detailed insights, check out Karatsu Climate.