Jeju weather in September

In September, Jeju sees average daytime highs of 24°C and overnight lows near 22°C, with 165 mm of rain across 11.1 wet days and about 12.2 hours of daylight. It is the 3rd-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 26°C in the first days to 23°C by the end. The sky is clear or mostly clear about 36% of the time in September, and the air most often feels muggy.

Daylight stretches from about 12 h 42 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Jeju's 2nd-clearest and 7th-windiest month. For the whole year in context, see Jeju's year-round climate.

Daytime high
24°
3rd warmest
Overnight low
22°
10th coldest
Rainfall
165 mm
11.1 wet days
Daylight
12 h 12 min
6:22 AM – 6:34 PM
Cloud cover
57%
2nd clearest
Wind
17 km/h
7th windiest
Solar energy
4.18 kWh/m²
Travel score
6.7
out of 10

Jeju is city in South Korea.

Density
500/km²
people per km²

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 26°C in the first days to 23°C by the end.

A typical September day in Jeju reaches about 24°C in the afternoon and slips back to 22°C overnight — a 2°C spread between the day's warmth and the night's chill. On most days the high lands between 22°C and 26°C. Set against its neighbours, September runs about 3°C cooler than August and about 4°C warmer than October.

15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12624
22624
32623
42623
52623
62623
72523
82523
92523
102523
112522
122522
132522
142522
152422
162422
172422
182422
192421
202421
212421
222321
232321
242321
252321
262320
272320
282320
292320
302220

How September really feels in Jeju

Once humidity and wind are folded in, September averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Jeju weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / 7311.62.6101.1
Feb / 649.31.710.81.5
Mar11° / 9510.30.411.72.9
Apr15° / 11°1028.9012.84.6
May19° / 15°1098.8013.76.2
Jun22° / 19°18911.6014.26.1
Jul26° / 24°18412.10146.2
Aug27° / 25°16813.7013.25.9
Sep24° / 22°16511.1012.26.7
Oct20° / 17°796.8011.26.9
Nov15° / 12°708.8010.34.7
Dec10° / 68111.19.82.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 36% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 49%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14555
24654
34654
44654
54654
64753
74753
84852
94951
105050
115050
125050
135050
145050
155149
165149
175149
185149
195248
205248
215248
225347
235446
245446
255446
265446
275446
285545
295644
305644

Chance of precipitation in September

Any precipitation

Jeju gets around 165 mm of rain over 11.1 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 36% and peaks near 43% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
143
242
341
441
540
640
740
840
940
1039
1139
1239
1338
1438
1537
1637
1736
1836
1935
2035
2134
2234
2333
2432
2532
2631
2731
2831
2930
3030

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels muggy — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the muggy band about 31% of days. Sticky, muggy-or-worse air turns up on roughly 60% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1009363520
20110373418
30111393317
40112403215
50113403213
60215413111
70216413110
8031741308
9031841307
10142040296
11152139285
12162338284
13172437274
14282535263
152102733263
163112832252
173122930242
184143028232
194153027221
205163126211
215173225191
226193224181
237203323171
248213322161
259223321141
2610243320131
2711253220120
2812263219110
2914273119100
301527301890

Wind in September

Winds average 17 km/h in September.

Across September, daily wind ranges from about 16 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

0510152025151015202530
Wind speed (km/h)Feels
116light breeze
216light breeze
316light breeze
416light breeze
516light breeze
616light breeze
716light breeze
816light breeze
916light breeze
1017light breeze
1117light breeze
1217light breeze
1317light breeze
1417light breeze
1517light breeze
1617light breeze
1718light breeze
1818light breeze
1918light breeze
2018light breeze
2118light breeze
2218light breeze
2318light breeze
2418light breeze
2518light breeze
2618light breeze
2718light breeze
2818light breeze
2918light breeze
3018light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 42 min at the start of September to 11 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 60 minutes over September. Sunrise moves from 6:12 AM to 6:32 AM, and sunset from 6:56 PM to 6:14 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.76:126:56
212.76:126:54
312.76:136:53
412.66:146:51
512.66:156:50
612.66:156:49
712.56:166:47
812.56:176:46
912.56:176:44
1012.46:186:43
1112.46:196:42
1212.36:196:40
1312.36:206:39
1412.36:216:37
1512.26:216:36
1612.26:226:34
1712.26:236:33
1812.16:236:31
1912.16:246:30
2012.16:256:29
2112.06:266:27
2212.06:266:26
2312.06:276:24
2411.96:286:23
2511.96:286:21
2611.86:296:20
2711.86:306:19
2811.86:316:17
2911.76:316:16
3011.76:326:14

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.18 kWh/m².

For context, solar energy here swings from a low near 2.09 kWh/m² to a high of 5.73 kWh/m² in May across the year — September's 4.18 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.5Bright
24.5Bright
34.4Bright
44.4Bright
54.4Bright
64.4Bright
74.3Bright
84.3Bright
94.3Bright
104.3Bright
114.3Bright
124.2Bright
134.2Bright
144.2Bright
154.2Bright
164.2Bright
174.2Bright
184.2Bright
194.1Bright
204.1Bright
214.1Bright
224.1Bright
234.1Bright
244.1Bright
254.1Bright
264.0Bright
274.0Bright
284.0Bright
294.0Bright
304.0Moderate
Planning a trip in September

Hazard calendar for Jeju

In seasonPeak

In September, Jeju sits inside its pacific typhoon and rainy season season. The full year is below, with each hazard's peak months called out.

Jeju sits in the Pacific typhoon belt; the season peaks July–October.

Jeju's rainy season runs March–September, when most of the year's rain falls.

Pacific typhoon
Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Jeju?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

6.7
Sightseeing
2nd-best month of the year
5.7
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Jeju for sightseeing.

What to pack for Jeju in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Jeju sees daytime highs around 24°C and nights near 22°C. Worth packing: light clothes and rain gear. About 11 days see rain.

light clothesrain gear

Sea temperature near Jeju in September

The nearest coast averages about 25°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 16 km away) is warmest in August at about 27°C and coldest in March near 14°C.

It's comfortable for a long swim from Jun 18 to Nov 4 — about 4.6 months when the water holds above 20°C.

10°15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan15Cool
Feb14Bracing
Mar14Bracing
Apr14Bracing
May16Cool
Jun20Cool
Jul24Refreshing
Aug27Warm
Sep25Warm
Oct22Refreshing
Nov19Cool
Dec17Cool

UV index in Jeju in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Jeju peaks around July 16 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateJul 16UV 10Dec 21UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar6High
Apr7High
May8Very high
Jun8Very high
Jul10Very high
Aug8Very high
Sep9Very high
Oct6High
Nov4Moderate
Dec3Moderate

Air quality in Jeju in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Jeju is worst in March — around 30 µg/m³ PM2.5 (moderate), about 2.3× the cleanest month (July, 13 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateMar 2130 µg/m³Jul 2413 µg/m³
PM2.5 (µg/m³)Level
Jan21Moderate
Feb25Moderate
Mar30Moderate
Apr29Moderate
May23Moderate
Jun18Moderate
Jul13Moderate
Aug13Moderate
Sep14Moderate
Oct15Moderate
Nov18Moderate
Dec16Moderate
Location & terrain

Where is Jeju?

Jeju sits at 33.5°N, 126.5°E, 19 m above sea level, in South Korea. The nearest listed city is Ido-dong, 1.0 km away.

Haenam

Topography around Jeju

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Jeju.

Within 3 km, the terrain around Jeju has only modest variations in elevation — a maximum elevation change of 141 m around an average of 43 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,836 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,915 m.

The land around Jeju is covered by artificial surfaces (51%) and water (29%) within 3 km, water (47%) and trees (36%) within 16 km, and water (88%) within 80 km.

3 km
141 m
16 km
1,836 m
80 km
1,915 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Ido-dong 1.0 km · Ora-dong 3.0 km · Seodong 4.0 km · Ara-dong 5.0 km · Tallang-dong 5.0 km · Gaigeturi 20 km · Seogwipo 29 km · Haenam 118 km

South Korea travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / F
220 V · 60 Hz
Prices
≈ 57% of US
price level, 2025
GDP per capita
$36,227
2025
Happiness
6.0 / 10
World Happiness, 2025
Safe drinking water
99%
of population, 2024
Homicide rate
0.5
per 100k, 2023
Road deaths
8.6
per 100k/yr, 2019
Income group
High
World Bank
English
Moderate
EF EPI 522
Religion
none 60%Protestant 17%Buddhist 16%Catholic 6%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Jeju (33.5097°, 126.5219°, elevation 19 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).