Last updated: October 30, 2025
In September, Incheon, South Korea experiences a delightful blend of warm temperatures and moderate humidity, making it an ideal time for outdoor activities. The maximum temperature can reach up to 31°C (87°F), while the average hovers around a comfortable 22°C (72°F). However, evenings can be cooler, with a minimum of 11°C (53°F). Travelers should be prepared for occasional rain, as the city sees about 133 mm (5.2 in) of precipitation across 9 days. With a humidity level of 77%, September’s weather offers a refreshing yet sometimes damp atmosphere, perfect for enjoying Incheon’s vibrant culture and natural beauty.
In September, Incheon, South Korea, experiences a delightful transition into autumn, marked by mild temperatures that invite outdoor activities. With a minimum of 11°C (53°F) and a comfortable average of 22°C (72°F), the weather is significantly warmer than the preceding months, although not as sweltering as the peak summer heat. The daily highs reach up to 31°C (87°F), providing a perfect warm environment for strolling through beautiful parks or savouring local cuisine at bustling street markets. As the month progresses, these temperatures begin to cool, gently hinting at the upcoming fall season while still offering plenty of sunny days to enjoy. This balance of warmth and the onset of autumn colors creates a picturesque backdrop, making September a favored time for visitors and locals alike.
In September, Incheon experiences a notable shift in its climatic patterns, receiving 133 mm (5.2 in) of precipitation over 9 days. This volume showcases a marked decrease when compared to the intense downpours of July and August, which often bring the highest rainfall amounts of the year at 232 mm and 256 mm, respectively. The transition into September is characterized by fluctuating weather, as the monsoon season gradually recedes, leading to a more temperate and varied climate. This month lays the foundation for the onset of drier autumn months, as seen in the sharp decline of rainfall in October's mere 59 mm. Overall, September serves as a bridge, balancing between the heavy summer rains and the approaching cooler, drier season.
In September, Incheon experiences a noticeable shift in humidity levels as the summer heat begins to wane, with an average of 77%. This marks a decline from the peak months of July and August, where humidity levels soared to 91%. As the transition into autumn unfolds, September's humidity is higher than earlier in the year, notably surpassing the lower rates of 65% recorded in March and February. This gradual easing creates a more comfortable atmosphere, allowing residents to enjoy the early fall scenery without the oppressive weight of summer's humidity. The trend of rising humidity through spring and summer peaks before a subtle drop, suggesting an upcoming seasonal refresh as the months turn cooler.
As September arrives in Incheon, the UV Index is still notably high at 9, categorizing exposure as very high and necessitating caution, with a burn time of just 15 minutes under direct sunlight. This represents a slight decrease from the extreme levels observed in the sweltering summer months of July and August, yet remains indicative of the lingering warmth and potent sun. While the summer peaks at 11 indicate a pressing need for sun protection, the transition into autumn evident in September’s figures shows a gradual decline, revealing a pattern of increased UV intensity from early spring through the height of summer before tapering off. Residents and visitors should remain vigilant, adopting sun safety measures to prevent skin damage, especially during midday hours. For more information on the UV Index throughout the year, visit Incheon UV Index.
UV Risk Categories
As summer transitions to autumn, September in Incheon, South Korea, offers a delightful blend of warm weather and abundant sunshine, totaling 262 hours of sunlight. This stands as a charming shift from the peak of summer in June, which boasts the highest sun exposure at 317 hours, while still maintaining a pleasant brightness that lingers into the crisp October days. Following the summer months, September's sunlight diminishes slightly yet remains significantly higher than the winter months, demonstrating a gradual but steady decline in daylight as the year winds down. With clear skies and a comfortable climate, September is a perfect time to enjoy outdoor activities before the chill of fall fully sets in.
In September, the likelihood of sunny weather in Incheon, South Korea, stands at 42%, a modest improvement from the summer months of July and August, which see a decline to 32% and 33%, respectively. This increase hints at a gradual transition into autumn, where clear skies start to appear with greater regularity. Compared to earlier months like May and June, both hovering around 39%, September offers a slightly brighter outlook. However, it’s still less sunny than the later autumn months, where the chances rise to 46% in October and reach 61% in November. Overall, while September may not guarantee sunshine, it represents a refreshing shift towards clearer days as summer wanes.
As summer fades into autumn, September in Incheon, South Korea, marks a subtle transition in daylight duration. With 12 hours of daylight, September reflects a gentle decline from the peak of 14 hours experienced in the previous months of June, July, and August. This gradual reduction signals the onset of shorter days as we move towards the cooler months of October and November, which each offer 11 and 10 hours of daylight, respectively. The rhythm of the seasons is evident, as daylight progressively wanes, inviting a shift in both the landscape and lifestyle of the region.
As summer fades into autumn, September in Incheon greets residents and visitors with a gentle shift in the breeze, displaying an average wind speed of 3.0 m/s (7 mph). This slight uptick from the calmer summer months indicates a refreshing change, as the winds begin to pick up slightly compared to the lows of July and August. Following a predominantly tranquil summer, September's winds serve as a prelude to the brisk gusts of fall, reminiscent of the lively whispers of the changing season. Interestingly, September winds also mirror the speeds seen in April and November, signaling a harmonious rhythm in Incheon’s climatic dance through the year, where each month plays its distinctive yet interconnected role in shaping the city’s atmospheric tapestry.
Weather in Incheon varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Incheon, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present a stark contrast in weather patterns. In September, the temperatures range from a minimum of 11°C (53°F) to a maximum of 31°C (87°F), with an average of 22°C (72°F), accompanied by relatively high humidity at 77% and 133 mm (5.2 in) of precipitation over 9 days. In contrast, January experiences much colder conditions, featuring temperatures that dip to a minimum of -16°C (3°F) and peak at 12°C (54°F), resulting in an average of -2°C (29°F). Precipitation during this month is significantly lower, with only 17 mm (0.7 in) over just 2 days, and humidity stands at 71%. For more detailed information about January weather, visit Incheon weather in January.
September and February present starkly contrasting weather conditions. In September, temperatures range from a minimum of 11°C (53°F) to a maximum of 31°C (87°F), with an average of 22°C (72°F). The month experiences significant rainfall, with a total precipitation of 133 mm (5.2 in) over about 9 days, contributing to a higher humidity level of 77%. In contrast, February is characterized by much colder weather, with temperatures fluctuating between a frigid -14°C (6°F) and a milder 15°C (59°F), averaging around 0°C (32°F). Precipitation is minimal during this month, amounting to only 21 mm (0.8 in) over 4 days, and humidity drops to 65%. Overall, the transition from September's warmth to February's chill underscores the dramatic seasonal changes experienced in Incheon. For more detailed information, you can visit Incheon weather in February.
The weather in September is significantly warmer and more humid compared to March. With an average temperature of 22°C (72°F) and maximums reaching up to 31°C (87°F), September enjoys a lively summer feel. In contrast, March experiences cooler temperatures, averaging only 6°C (44°F) and peaking at 19°C (66°F), making it a much chillier month. Additionally, September sees higher precipitation levels, with over 133 mm (5.2 in) of rain spread across about 9 days, while March has a relatively dry spell with just 44 mm (1.7 in) over 5 days. For more detailed information on March weather, check out Incheon weather in March.
In September, temperatures exhibit a broad range, with minimums reaching 11°C (53°F) and maximums soaring to 31°C (87°F), resulting in a comfortable average of 22°C (72°F). The month experiences significant precipitation at 133 mm (5.2 in) over about 9 days, coupled with a humidity level of 77%. In contrast, April offers cooler conditions, with minimum temperatures dropping to 1°C (33°F) and maximums peaking at 25°C (78°F), leading to a more modest average of 12°C (54°F). The month is drier, with only 49 mm (1.9 in) of rainfall over 6 days and a slightly lower humidity of 75%. For a closer look at April weather specifics, check out Incheon weather in April.
In comparing the weather of September and May, a noticeable difference in temperatures can be observed. September tends to be warmer, with average temperatures ranging from a minimum of 11°C (53°F) to a maximum of 31°C (87°F), whereas May has cooler temperatures, with a minimum of 7°C (44°F) and a maximum of 28°C (82°F). Precipitation levels are fairly similar, with September receiving 133 mm (5.2 in) over about 9 days and May slightly less, at 107 mm (4.2 in) over 8 days. Moreover, humidity levels are marginally higher in May at 81%, compared to September's 77%. For more detailed information about May weather, you can visit Incheon weather in May.
In comparing the weather between September and June, both months showcase similar maximum temperatures of around 31°C (87°F) and 31°C (88°F), respectively. However, September experiences a slightly cooler average temperature of 22°C (72°F), while June averages at 22°C (71°F). Notably, September is marked by higher precipitation levels at 133 mm (5.2 in) over 9 days, compared to June’s 77 mm (3.0 in) during the same number of days. Humidity levels are also higher in June, reaching 85%, whereas September's humidity stands at 77%. For more detailed insights on the weather during June, you can visit Incheon weather in June.
When comparing the weather in September and July, a noticeable difference in temperature and humidity can be observed. September tends to be milder, with average temperatures ranging from a minimum of 11°C (53°F) to a maximum of 31°C (87°F), while July experiences warmer conditions, with temperatures ranging from 19°C (66°F) to 35°C (95°F). Additionally, July is characterized by higher humidity levels at 91%, compared to September's 77%. Precipitation is also more significant in July, with 232 mm (9.1 in) over 14 days, whereas September sees 133 mm (5.2 in) of rain spread across 9 days. For more details on July's weather patterns, you can visit Incheon weather in July.
When comparing the weather in September to August, it's clear that September experiences cooler temperatures, with a minimum of 11°C (53°F) and a maximum of 31°C (87°F), significantly lower than August's range of 17°C (63°F) to 36°C (97°F). Additionally, September is marked by an average temperature of 22°C (72°F) compared to August's warmer average of 27°C (80°F). While both months see considerable rainfall, September receives 133 mm (5.2 in) over 9 days, which is notably less than the 256 mm (10.1 in) over 15 days in August. Humidity is also higher in August at 91%, compared to 77% in September. Overall, September offers a more comfortable climate, making it a more pleasant time for outdoor activities. For more detailed insights, check out Incheon weather in August.
September brings warmer temperatures with a minimum of 11°C (53°F) and an average high of 31°C (87°F), while October experiences cooler conditions, with temperatures dropping to a minimum of 2°C (36°F) and an average high of 28°C (82°F). Humidity remains fairly similar, with September at 77% and October slightly higher at 79%. Additionally, September sees more precipitation, totaling 133 mm (5.2 in) over 9 days, compared to October’s 59 mm (2.3 in) over just 6 days, making October feel drier overall. For more detailed information, check out the Incheon weather in October.
September and November showcase a stark contrast in weather conditions. September boasts a warm climate with average temperatures reaching 22°C (72°F) and maximums peaking at 31°C (87°F), while nights can be mild with a minimum of 11°C (53°F). However, September also experiences higher humidity at 77% and more rainfall, with 133 mm (5.2 in) over about 9 rainy days. In contrast, November brings a notable drop in temperatures, averaging around 8°C (47°F) and experiencing colder nights with minimums dipping to -5°C (23°F). Despite less precipitation, totaling 53 mm (2.1 in) over just 5 days, November maintains a slightly higher humidity level at 80%. For more details, visit Incheon weather in November.
September and December present stark contrasts in weather, reflecting the transition from summer to winter. In September, temperatures range from a mild 11°C (53°F) at night to a warm 31°C (87°F) during the day, with an average of 22°C (72°F). Humidity is high at 77%, and the month sees 133 mm (5.2 in) of rainfall over nine days, contributing to a lush, vibrant atmosphere. In stark contrast, December features much colder temperatures, plummeting to a minimum of -14°C (7°F) and averaging around 0°C (33°F), with a maximum of just 12°C (54°F). Precipitation is significantly lower, with only 24 mm (0.9 in) spread over five days, and humidity sinks to 74%. For more detailed insights into Incheon weather in December, visit the provided link.
As summer transitions into autumn, September in Incheon brings a delightful change in weather characterized by warm days and cooler nights. While temperatures can soar to a high of 31°C, the average settles comfortably at 22°C, offering a pleasant escape from the peak heat of summer. However, with an average humidity of 77% and a total of nine rainy days, the month also sees an increase in precipitation. This unique blend of warm weather and occasional rain distinguishes September from the drier, hotter months of July and August, making it a lovely time to explore Incheon's vibrant landscapes. For more details on what to expect throughout the year, visit Incheon Climate.