Last updated: October 30, 2025
September in Jeju City, South Korea offers a pleasant yet humid climate, with average temperatures hovering around 23°C (74°F). The month sees highs of 28°C (83°F) and lows dipping to 18°C (65°F), making it comfortable for outdoor activities. However, expect significant rainfall, with about 298 mm (11.7 in) falling over 15 days, contributing to a humidity level of 84%. These conditions create a lush atmosphere, ideal for exploring Jeju's stunning landscapes but be prepared for the occasional downpour.
In September, Jeju City experiences a delightful transition from the summer heat, with minimum temperatures around 18°C (65°F) and averages reaching 23°C (74°F), making it a comfortable time to explore the island. As the max temperatures peak at 28°C (83°F), the weather remains warm without the stifling humidity of July and August, inviting both locals and tourists to enjoy outdoor activities. The crisp, refreshing evenings serve as a perfect backdrop for night markets and seaside strolls, signaling the beginning of autumn while still allowing for sun-kissed adventures. This month stands out as an appealing time to visit, balancing warmth with the gentle onset of cooler days ahead.
In Jeju City, South Korea, September marks a significant peak in precipitation, with an impressive 298 mm (11.7 in) of rainfall accumulated over 15 days. This surge is notably higher than the preceding months, reflecting a transitional weather pattern as summer fades and autumn approaches. The rainy season appears to reach its zenith during this time, following a gradual increase from 197 mm (7.7 in) in August. The consistent downpours not only contrast sharply with January's modest 58 mm (2.3 in) but also highlight Jeju's reputation for dramatic seasonal shifts. With each wet day, the island transforms, showcasing its lush landscapes and vibrant flora, making September a remarkable month for both nature enthusiasts and travelers alike.
In September, Jeju City experiences a noticeable dip in humidity, with levels averaging 84%. This reduction follows the sweltering summer months of July and August, where humidity peaks at an intense 98% and 96%, respectively. As autumn approaches, the air begins to feel crisper, with September's humidity providing a refreshing contrast to the preceding months. This trend of decreasing humidity continues into the fall, dropping to 78% in October and further to 73% in November, signaling a transition towards drier, more comfortable conditions. Overall, September serves as a pivotal point, bridging the humid summer and the pleasant autumn in this beautiful island city.
In September, Jeju City experiences a UV Index of 10, categorizing it as very high and indicating a burn time of just 15 minutes. This trend follows the peak summer months of June and July, where the UV Index reached extreme levels of 11 and 12, respectively. As the season transitions to autumn, there's a slight decrease in UV intensity, yet still maintaining a high risk for sunburn, reminding residents and visitors alike to take precautions. Notably, September marks a significant drop from the summer’s extremes, but vigilance is still encouraged for outdoor activities. If you're planning to enjoy the beautiful landscapes of Jeju during this month, be sure to check the forecast and stay informed through the Jeju City UV Index.
UV Risk Categories
As summer fades into autumn, September in Jeju City reveals a charming blend of warmth and sunlight, offering residents and visitors alike a delightful 266 hours of sunshine. Following the peak of the sunniest month, August, which boasts a vibrant 318 hours, September reflects a gentle decrease, yet continues to bathe the island in a golden glow. This pattern underscores Jeju's unique climate, where lasting sunshine persists even as temperatures begin to cool down. In fact, September maintains far more daylight hours than the earlier months of the year, a testament to the island's luminous appeal as it transitions into the heart of fall. The gradual shift showcases a rhythm of light and warmth that defines Jeju, inviting everyone to relish the serene beauty of the island before winter's onset.
As September rolls into Jeju City, the probability of sunny weather hovers around a modest 35%, mirroring the inconsistent sunshine of late summer. This marks a slight uptick, suggesting a transition toward clearer skies as autumn approaches. Notably, the chance of sunshine increases significantly in the following months, with October boasting an impressive 56% likelihood. This trend highlights the shift in seasons, where the more temperate autumn months provide greater opportunities for outdoor activities and exploration, making September a subtly optimistic time for sun seekers in Jeju.
In September, Jeju City experiences a pleasant 12 hours of daylight, signaling a gradual shift as summer gives way to autumn. The trend of steadily increasing daylight from 10 hours in January peaks in June and July with 14 hours each, creating an abundant summer experience. However, as the days shorten, September sees a subtle decline from the 13 hours of daylight enjoyed in August, hinting at the upcoming seasonal changes. This rhythm of daylight not only marks the passage of time but also invites locals and visitors alike to savor the vibrant natural beauty of Jeju as it transitions toward the cooler months.
September in Jeju City, South Korea ushers in a refreshing shift as the average wind speed climbs to 5.6 m/s (13 mph), a notable increase following the calmer summer months. This slight resurgence in wind signals the transition into autumn, bringing a crispness to the air that invigorates the senses. The wind speeds in September are notably higher than the preceding summer average of 4.3 m/s (9.6 mph), yet still remain below the robust gusts characteristic of winter months. As the island prepares for the changing seasons, the pleasant breeze becomes perfect for outdoor explorations, making it an ideal time for visitors to experience the natural beauty and vibrant culture of Jeju.
Weather in Jeju City varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Jeju City, focusing on differences in temperature, rainfall, humidity, and UV levels.
September and January present strikingly different weather patterns. In September, temperatures range from a mild 18°C (65°F) at night to a warm 28°C (83°F) during the day, with an average of 23°C (74°F). The month also sees considerable rainfall, with 298 mm (11.7 in) spread over 15 days and humidity levels reaching 84%. In contrast, January experiences much colder weather, with temperatures ranging from a low of -2°C (29°F) to a maximum of 19°C (66°F), averaging just 6°C (44°F). Rainfall is significantly less frequent, totaling only 58 mm (2.3 in) over 10 days, and humidity drops to 72%. For more details about the weather in January, you can visit Jeju City weather in January.
September and February present strikingly different weather patterns. In September, temperatures range from a mild minimum of 18°C (65°F) to a warm maximum of 28°C (83°F), with an average of 23°C (74°F). This month also sees significant rainfall, with 298 mm (11.7 in) over approximately 15 days, leading to a high humidity of 84%. In contrast, February offers much cooler conditions, with temperatures ranging from a chilly minimum of -1°C (31°F) to a maximum of 17°C (63°F), averaging just 7°C (44°F). February experiences considerably less precipitation, totaling 59 mm (2.3 in) over 9 days, and lower humidity at 70%. For more detailed information, you can visit Jeju City weather in February.
When comparing the weather in September and March, it’s clear that September offers significantly warmer temperatures, with a minimum of 18°C (65°F) and an average of 23°C (74°F), peaking at 28°C (83°F). In contrast, March features much cooler weather, with temperatures ranging from a minimum of 3°C (37°F) to a maximum of 18°C (65°F) and an average of only 10°C (51°F). Additionally, September experiences higher precipitation levels at 298 mm (11.7 in) over 15 days, while March sees a milder 101 mm (4.0 in) across 11 days. Humidity levels also differ, with September at 84% compared to March's 73%. For a detailed look into the climate, check out Jeju City weather in March.
When comparing the weather in September and April, a stark contrast emerges. September boasts warmer temperatures, with an average around 23°C (74°F), reaching heights of 28°C (83°F), while April's temperatures are considerably cooler, peaking at only 20°C (69°F) and averaging 13°C (57°F). Additionally, September is characterized by significantly higher precipitation, totaling 298 mm (11.7 in) over 15 days, compared to April's more manageable 91 mm (3.6 in) across just 7 days. Despite the slight difference in humidity levels—84% in September and 83% in April—April's cooler climate provides a refreshing break from the warmth of late summer. For a more detailed look at April weather specifics, visit Jeju City weather in April.
September and May present contrasting weather patterns, showcasing the transition between summer and autumn. In September, temperatures range from a minimum of 18°C (65°F) to a maximum of 28°C (83°F), offering a warm average of 23°C (74°F). This month also experiences substantial rainfall, with 298 mm (11.7 in) over approximately 15 days and humidity levels at a high 84%. In contrast, May is cooler, with temperatures starting at a minimum of 10°C (51°F) and peaking at 24°C (75°F), leading to a lower average of 17°C (63°F). Precipitation is significantly less in May, with only 92 mm (3.6 in) over 9 days, and humidity is slightly higher at 89%. For more detailed insights, you can check Jeju City weather in May.
When comparing the weather in September and June, September tends to be warmer with an average temperature of 23°C (74°F), peaking at 28°C (83°F), while June has a slightly cooler average of 21°C (70°F) with a maximum of 26°C (79°F). Precipitation levels are significantly higher in September, with 298 mm (11.7 in) spread over 15 days, compared to June's 141 mm (5.6 in) over just 10 days. Both months exhibit high humidity, with September at 84% and June reaching 93%, making June feel a bit more humid overall. For a detailed look at the weather specifically in June, visit Jeju City weather in June.
When comparing the weather in September to that of July, September tends to be slightly cooler, with average temperatures ranging from a minimum of 18°C (65°F) to a maximum of 28°C (83°F), while July experiences warmer temperatures, averaging from a minimum of 19°C (67°F) to a maximum of 31°C (88°F). Additionally, September sees significantly more precipitation, with 298 mm (11.7 in) over 15 days, compared to July's 170 mm (6.7 in) over 14 days. Humidity levels are also notably different; July is quite humid at 98%, while September has a more moderate humidity level of 84%. For a closer look at July's weather specifics, you can visit Jeju City weather in July.
In comparing September to August, September experiences slightly cooler temperatures with a minimum of 18°C (65°F) and an average of 23°C (74°F), while August enjoys warmer conditions, with a minimum of 22°C (72°F) and an average of 27°C (81°F). Additionally, September sees a significant increase in precipitation, measuring 298 mm (11.7 in) over 15 days, compared to the 197 mm (7.7 in) that falls in August, also over 15 days. Humidity levels are notably high in both months, but August is slightly more humid at 96% versus September’s 84%. For a detailed look at the weather conditions specific to August, you can refer to Jeju City weather in August.
September and October exhibit contrasting weather patterns. In September, temperatures are warmer, with minimums around 18°C (65°F) and averages reaching 23°C (74°F), while maximums can climb to 28°C (83°F). However, this month also brings significant rainfall, with precipitation measuring 298 mm (11.7 in) over 15 days and a high humidity of 84%. In contrast, October sees cooler temperatures, with minimums dropping to 11°C (53°F) and an average temperature of 19°C (66°F), though maximums remain relatively high at 27°C (81°F). Rainfall decreases sharply to 109 mm (4.3 in) over just 9 days, and humidity levels drop slightly to 78%. For more detailed weather information, you can check Jeju City weather in October.
In September, the weather is warmer and significantly more humid, with temperatures ranging from a minimum of 18°C (65°F) to a maximum of 28°C (83°F) and an average of 23°C (74°F). The month is also characterized by higher precipitation, with around 298 mm (11.7 in) of rain falling over 15 days, contributing to a humidity level of 84%. In contrast, November brings much cooler temperatures, with a minimum of 6°C (43°F) and an average of 14°C (57°F), peaking at 22°C (71°F). Precipitation drops to 46 mm (1.8 in), spread over just 7 days, leading to a decrease in humidity to 73%. For more details on November weather in Jeju, you can check Jeju City weather in November.
The weather in September is notably warmer and more humid compared to December. With temperatures ranging from a minimum of 18°C (65°F) to a maximum of 28°C (83°F), September averages around 23°C (74°F). This month also experiences significant rainfall of 298 mm (11.7 in) over 15 days, contributing to a high humidity level of 84%.
In contrast, December brings cooler temperatures, with a minimum of 0°C (33°F) and a maximum of 20°C (68°F), yielding an average temperature of 9°C (48°F). The precipitation drops to 61 mm (2.4 in) over about 10 days, and the humidity decreases to 71%. For a more detailed look at December weather in Jeju City, you can visit Jeju City weather in December.
As summer transitions to autumn, September in Jeju City offers a unique blend of warmth and humidity, distinguishing it from the drier months preceding it. With temperatures comfortably averaging around 23°C (74°F), this month is characterized by its increased rainfall, with approximately 15 days of precipitation that adds a lush vibrancy to the island's scenery. The humidity reaches a notable 84%, contributing to the feeling of a tropical paradise but also hinting at the approaching cooler season. For those curious about the year-round climate patterns, more details can be found at Jeju City Climate.