Last updated: October 30, 2025
In September, Ulsan, South Korea, experiences a dynamic blend of weather patterns, characterized by a maximum temperature peaking at 30°C (87°F) and an average of 22°C (73°F), providing a warm backdrop for the transition into autumn. With a minimum temperature of 13°C (56°F), the nights bring a cooler respite. September also registers a significant precipitation amount of 236 mm (9.3 in), spread over 12 days, contributing to the region's lush greenery. The humidity levels hover around 80%, creating a humid atmosphere that, while sometimes uncomfortable, underscores the tropical essence of early fall in Ulsan.
In September, Ulsan experiences a pleasant transition into autumn, boasting temperatures that embody the best of early fall. With daily minimums around 13°C (56°F) and average highs peaking at 30°C (87°F), the month showcases a comfortable warmth, making outdoor activities particularly enjoyable. After the scorching heat of summer, where temperatures can soar above 36°C (98°F) in July and August, September's milder climate encourages exploration of Ulsan's beautiful landscapes and vibrant city life. This warm yet manageable weather strikes a harmonious balance, marking a perfect time to savor both sunny days and the crisp beginnings of autumn in South Korea.
In September, Ulsan experiences a significant uptick in precipitation, totaling 236 mm (9.3 in) over 12 days of rain. This marks a continuation of the wet summer season, with September rainfall nearly rivaling that of July's peak. While the summer months are characterized by abundant rainfall, September often serves as a transitional period, showcasing a blend of lingering monsoon influences and the onset of autumn. Comparatively, this month sees a drop in precipitation days from 15 in August, indicating that, although the total volume remains high, the rain tends to be concentrated in fewer storms. With the city’s lush landscapes benefiting from this moisture, September sets the stage for a vibrant and colorful autumn.
In Ulsan, South Korea, September marks a notable shift in humidity as summer wanes, with levels averaging around 80%. This represents a slight dip from the sweltering heights of July and August, which boast humidity levels of 95% and 93%, respectively. While September's humidity remains relatively high compared to the cooler months, such as January and February, it signals the gradual transition towards a more comfortable climate. The trend through the year showcases an increase in humidity from 65% in March to the peak of summer, before gently ebbing in the fall. As the month unfolds, residents can expect a mix of warmth and moisture, paving the way for the crisp autumn air ahead.
As September rolls into Ulsan, South Korea, residents and visitors alike should be mindful of the very high UV Index rating of 10, which translates to a burn time of just 15 minutes for unprotected skin. This trend of increasing UV intensity throughout the summer months continues into early fall, with a slight ease from the extremes of July and August, where the UV Index peaked at 12. Unlike the cooler months that follow, September still calls for precautionary measures against sun exposure, mirroring the patterns observed from April to June. It’s a vital reminder to stay sun-smart during this transitional period and to plan outdoor activities accordingly. For more information on the UV Index throughout the year, check out Ulsan UV Index.
UV Risk Categories
As summer transitions to autumn, September in Ulsan, South Korea, welcomes a gentle dip in sunshine hours, offering approximately 248 hours of radiant light. While this marks a noticeable reduction from August's generous 299 hours, it's still well above the winter months, indicating that the warm embrace of sunshine lingers longer than in the cold season. This month reflects a gradual decline in daylight that began in July, yet September's brightness still resonates with the vibrant energy of late summer. As nature begins to shift and prepare for the coming chill, Ulsan captures the last golden rays, making it a beautiful time for outdoor exploration before the days grow shorter.
In Ulsan, South Korea, the likelihood of experiencing sunny weather in September stands at 28%, which follows a somewhat dreary summer with July and August showing notably low chances of sunshine at 20% and 24%, respectively. As the year progresses, September marks the transition into a period of slightly improved clarity, but doesn't yet reach the more favorable conditions seen in October, which basks in a more hopeful 52% chance of sunshine. This pattern suggests that while September can still be cloudy, it serves as a stepping stone towards the brighter days of fall, inviting locals and visitors alike to anticipate the sun returning in the following month.
In September, daylight in Ulsan, South Korea, offers a gentle transition as it begins to wane from the peak summer months. With approximately 12 hours of daylight, the city experiences a gradual decline following the summer highs of 14 hours in June, July, and August. This decrease marks the onset of autumn, where the days shorten progressively towards winter. Interestingly, after a steady increase from 10 hours in January to 14 hours in May, Ulsan's daylight duration features a more nuanced rhythm, subtly shifting towards a cozy, twilight ambiance that characterizes the upcoming cooler months.
As summer gives way to fall, September in Ulsan, South Korea presents a refreshing change in the air, with an average wind speed of 3.6 m/s (8 mph). This marks a notable increase compared to the lighter breezes of July and August, which hovered around 2.8 to 2.9 m/s. The gentle rise in wind speed during September signals a transition, hinting at the approaching cooler months. Interestingly, it also foreshadows a shift towards more dynamic weather patterns, as earlier months like May and June, where winds were even lighter at 3.0 m/s and 2.6 m/s, give way to a crispness that invigorates the atmosphere. With this uptick, September stands out as a time when the winds begin to sigh of autumn’s arrival, creating a perfect backdrop for outdoor activities in the coastal city.
Weather in Ulsan varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Ulsan, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present stark contrasts in weather. In September, temperatures range from a mild 13°C (56°F) at night to a warm peak of 30°C (87°F) during the day, accompanied by high humidity levels at 80%. This month also sees significant rainfall, with 236 mm (9.3 in) over 12 days, creating a lush and vibrant atmosphere. Conversely, January showcases a chilly climate, with temperatures dropping to a minimum of -12°C (11°F) and averaging just 3°C (37°F), with a maximum of 16°C (62°F). Precipitation is much lower, totaling only 32 mm (1.2 in) over just 3 days and lower humidity at 72%. To learn more about Ulsan's January weather, visit Ulsan weather in January.
September and February present stark contrasts in weather. In September, temperatures range from a chilly 13°C (56°F) at night to a warm 30°C (87°F) during the day, with an average of 22°C (73°F). This month also sees significant rainfall, accumulating to 236 mm (9.3 in) over approximately 12 days, alongside high humidity levels at 80%. In contrast, February offers a breadth of temperatures from a cold minimum of -9°C (15°F) to a pleasant maximum of 23°C (73°F), with an average around 4°C (40°F). Precipitation is minimal in February, totaling just 39 mm (1.5 in) over 4 days, and humidity is lower at 67%. For more detailed information, check Ulsan weather in February.
September and March present strikingly contrasting weather conditions. In September, temperatures range from a mild 13°C (56°F) to a warm 30°C (87°F) with an average of 22°C (73°F), complemented by high humidity levels of 80%. This month also sees substantial precipitation, with 236 mm (9.3 in) falling over 12 days. In contrast, March experiences much cooler temperatures with a minimum of -2°C (29°F) and a maximum of 22°C (73°F), but with a notably lower average of 9°C (49°F). Precipitation is also reduced in March, amounting to 86 mm (3.4 in) over just 8 days, and the humidity drops to 65%. For more detailed information about March weather, please visit Ulsan weather in March.
In comparing the weather between September and April, there are notable differences in temperature and precipitation. September experiences a mild average temperature of 22°C (73°F) with highs reaching up to 30°C (87°F), while April has a cooler average of 14°C (57°F) and maximum temperatures of 26°C (80°F). Precipitation also varies significantly; September sees a substantial 236 mm (9.3 in) of rain over 12 days, in contrast to April's lighter 87 mm (3.4 in) across just 7 days. Additionally, humidity levels are slightly higher in September at 80%, compared to 75% in April, contributing to a more humid feel in the early autumn months. For more specific weather details, you can refer to Ulsan weather in April.
In September, the weather tends to be warmer with average temperatures ranging from a minimum of 13°C (56°F) to a maximum of 30°C (87°F), while May experiences slightly cooler averages, with temperatures fluctuating between 6°C (43°F) and 33°C (92°F). September also sees significantly higher precipitation, with 236 mm (9.3 in) over 12 days compared to May's milder 80 mm (3.1 in) over just 8 days. Additionally, humidity levels remain high in both months, with September at 80% and May slightly higher at 83%. For more details on the weather specifics in May, check out Ulsan weather in May.
In comparing the weather of September and June, we see some notable similarities and differences. Both months have a minimum temperature of around 13°C (56°F) and an average temperature of approximately 22°C (73°F). However, June tends to be slightly warmer, with a maximum temperature reaching 32°C (90°F), compared to September's peak of 30°C (87°F).
In terms of precipitation, September is wetter with 236 mm (9.3 in) over 12 days, whereas June experiences less rain at 144 mm (5.7 in) across 10 days. Additionally, September has a humidity level of 80%, which is a bit lower than June’s higher humidity of 87%. For a more detailed look at June weather specifics, refer to Ulsan weather in June.
In comparing the weather between September and July, September tends to be milder with average temperatures ranging from a minimum of 13°C (56°F) to a maximum of 30°C (87°F), whereas July experiences warmer conditions, with temperatures ranging from a minimum of 17°C (63°F) to a scorching maximum of 36°C (98°F). Both months have significant rainfall, with September receiving about 236 mm (9.3 in) over 12 days and July slightly higher at 244 mm (9.6 in) across 14 days. Additionally, humidity levels are notably higher in July at 95%, compared to September's 80%, making July feel more oppressive. For a detailed look at July's weather, visit Ulsan weather in July.
In comparing the weather of September to that of August, we see a notable shift in temperatures and precipitation patterns. September experiences cooler temperatures, with a minimum of 13°C (56°F) and an average of 22°C (73°F), compared to August's warmer minimum of 19°C (66°F) and an average of 27°C (81°F). The maximum temperature in September reaches 30°C (87°F), significantly lower than August's peak of 36°C (98°F). Additionally, September receives more rainfall, totaling 236 mm (9.3 in) over 12 days, compared to August's 199 mm (7.8 in) over 15 days. Humidity levels also decrease from August's high of 93% to September's 80%, offering a slightly more comfortable feel. For more details on August weather, check out Ulsan weather in August.
September and October present a notable shift in weather patterns. In September, temperatures remain relatively warm, with a minimum of 13°C and an average of 22°C, peaking at 30°C. However, this month also sees significant rainfall, totaling 236 mm over 12 days and accompanied by high humidity at 80%. In contrast, October experiences cooler conditions, with a minimum temperature dropping to 5°C and an average of 17°C. Although the maximum temperature can still reach 30°C, the month is generally dryer, with only 100 mm of precipitation across 7 days and slightly lower humidity at 77%. For more specific details about October's weather, check out Ulsan weather in October.
September and November exhibit striking differences in weather patterns. In September, temperatures range from a mild 13°C (56°F) at night to a warm average of 22°C (73°F) during the day, peaking at a maximum of 30°C (87°F). However, this month also brings significant rainfall, with about 236 mm (9.3 in) spread over 12 days, contributing to a relatively high humidity level of 80%. In contrast, November ushers in a much cooler climate, with temperatures dipping to a minimum of -2°C (29°F) and averaging around 11°C (52°F). The maximum temperature reaches only 22°C (72°F), and the precipitation significantly decreases to 21 mm (0.8 in) over just 3 days, with humidity dropping slightly to 75%. For more detailed information, you can check Ulsan weather in November.
September weather is characterized by warm temperatures, with minima around 13°C (56°F) and maximums reaching up to 30°C (87°F), resulting in an average of 22°C (73°F). It tends to be quite humid at 80% and experiences significant rainfall, with 236 mm (9.3 in) of precipitation over about 12 days. In contrast, December brings a dramatic change, with temperatures dropping significantly; the minimum can fall to -9°C (17°F) and the maximum is capped at 18°C (64°F), yielding a much cooler average of 4°C (40°F). Additionally, December is drier, with only 23 mm (0.9 in) of rain over about 3 days and lower humidity at 73%. For more detailed insights, you can refer to Ulsan weather in December.
As September unfolds in Ulsan, it marks a transition from the sweltering summer to a more moderate climate. With temperatures cooling slightly, the average feels pleasantly mild, providing a refreshing contrast to the heat of previous months. However, the month also brings increased humidity and notable rainfall, with several days of precipitation that transform the landscape. This unique blend of warmth and moisture creates a vibrant atmosphere, making September an ideal time to experience Ulsan's natural beauty. For more detailed insights into the climate patterns throughout the year, visit Ulsan Climate.