Yesan weather in September

In September, Yesan sees average daytime highs of 26°C and overnight lows near 17°C, with 135 mm of rain across 7.9 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 3rd-wettest month of the year here.

Highs ease over the month, from about 28°C in the first days to 24°C by the end. The sky is clear or mostly clear about 37% of the time in September, and the air most often feels humid.

Daylight stretches from about 12 h 48 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Yesan's 7th-clearest and 11th-windiest month. For the whole year in context, see Yesan's year-round climate.

Daytime high
26°
4th warmest
Overnight low
17°
9th coldest
Rainfall
135 mm
7.9 wet days
Daylight
12 h 12 min
6:20 AM – 6:34 PM
Cloud cover
55%
7th clearest
Wind
8 km/h
11th windiest
Solar energy
4.32 kWh/m²
Travel score
7.0
out of 10

Yesan is human settlement in South Korea.

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 28°C in the first days to 24°C by the end.

A typical September day in Yesan reaches about 26°C in the afternoon and slips back to 17°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 22°C and 29°C. Set against its neighbours, September runs about 4°C cooler than August and about 6°C warmer than October.

10°15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12820
22820
32820
42720
52720
62719
72719
82719
92719
102719
112718
122618
132618
142618
152617
162617
172617
182617
192517
202516
212516
222516
232516
242515
252415
262415
272415
282414
292414
302314

How September really feels in Yesan

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.

Yesan weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -5°224.53.19.80.0
Feb / -3°274.21.710.60.4
Mar11° / 416.11.111.73.2
Apr18° / 697012.96.3
May24° / 13°777.1013.97.3
Jun28° / 18°1177.9014.56.5
Jul29° / 22°24615.5014.34.6
Aug30° / 23°23515013.44.6
Sep26° / 17°1357.9012.27.0
Oct20° / 10°565.2011.17.2
Nov12° / 466.70.4103.8
Dec / -3°235.12.69.50.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 37% 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 (%)
14456
24555
34555
44654
54654
64753
74852
84852
94852
104951
115050
125050
135050
145149
155149
165248
175347
185347
195446
205545
215545
225545
235545
245545
255545
265545
275446
285545
295545
305446

Chance of precipitation in September

Any precipitation

Yesan gets around 135 mm of rain over 7.9 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 27% and peaks near 39% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
139
238
337
436
534
633
732
831
931
1030
1129
1229
1328
1427
1527
1626
1725
1825
1924
2024
2123
2223
2322
2422
2522
2622
2721
2821
2920
3020

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the humid band about 27% of days. Sticky, muggy-or-worse air turns up on roughly 33% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1162340273
2172539253
3182739232
4292838212
52102937201
63113037181
73123136161
84143136151
95153235130
106173234120
117183232110
128203131100
131021312990
141123302880
151324302670
161526292460
171727282250
181929282050
192130271940
202231271730
212431261530
222632261320
232833251220
243133251020
25333324910
26353323810
27373322710
28403321610
29423220600
30453118500

Wind in September

Winds average 8 km/h in September.

Across September, daily wind ranges from about 8 km/h on the calmest days to 8 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
18calm
28calm
38calm
48calm
58calm
68calm
78calm
88calm
98calm
108calm
118calm
128calm
138calm
148calm
158calm
168calm
178calm
188calm
198calm
208calm
218calm
228calm
238calm
248calm
258calm
268calm
278calm
288calm
298calm
308calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 48 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 66 minutes over September. Sunrise moves from 6:08 AM to 6:32 AM, and sunset from 6:57 PM to 6:12 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.86:086:57
212.86:096:55
312.76:096:54
412.76:106:52
512.76:116:51
612.66:126:49
712.66:136:48
812.56:136:46
912.56:146:45
1012.56:156:43
1112.46:166:42
1212.46:176:40
1312.36:186:39
1412.36:186:37
1512.36:196:35
1612.26:206:34
1712.26:216:32
1812.26:226:31
1912.16:236:29
2012.16:236:28
2112.06:246:26
2212.06:256:24
2311.96:266:23
2411.96:276:21
2511.96:286:20
2611.86:286:18
2711.86:296:17
2811.76:306:15
2911.76:316:14
3011.76:326:12

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.32 kWh/m².

For context, solar energy here swings from a low near 2.21 kWh/m² to a high of 5.93 kWh/m² in May across the year — September's 4.32 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.3Bright
24.3Bright
34.3Bright
44.4Bright
54.4Bright
64.4Bright
74.4Bright
84.3Bright
94.3Bright
104.3Bright
114.3Bright
124.3Bright
134.3Bright
144.3Bright
154.3Bright
164.3Bright
174.3Bright
184.3Bright
194.3Bright
204.3Bright
214.3Bright
224.3Bright
234.2Bright
244.2Bright
254.2Bright
264.2Bright
274.2Bright
284.2Bright
294.1Bright
304.1Bright
Planning a trip in September

Hazard calendar for Yesan

In seasonPeak

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

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

Yesan's rainy season runs June–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 Yesan?

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

7.0
Sightseeing
3rd-best month of the year
6.5
Beach & pool
2nd-best month of the year

September is one of the better times to visit Yesan for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Yesan in September

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

In September, Yesan sees daytime highs around 26°C and nights near 17°C. Worth packing: light clothes. About 8 days see rain.

light clothes

Sea temperature near Yesan in September

The nearest coast averages about 23°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 42 km away) is warmest in August at about 25°C and coldest in February near 5°C.

It's comfortable for a long swim from Jul 4 to Oct 7 — about 3.2 months when the water holds above 20°C.

0°10°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan7Bracing
Feb5Bracing
Mar6Bracing
Apr8Bracing
May12Bracing
Jun18Cool
Jul22Refreshing
Aug25Warm
Sep23Refreshing
Oct19Cool
Nov15Cool
Dec11Bracing

UV index in Yesan in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Yesan peaks around July 24 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 23 at about 2 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateJul 24UV 8Dec 23UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May6High
Jun7High
Jul8Very high
Aug8Very high
Sep7Very high
Oct5High
Nov3Moderate
Dec2Low

Air quality in Yesan 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 Yesan is worst in March — around 92 µg/m³ PM2.5 (unhealthy), about 2.0× the cleanest month (July, 46 µg/m³).

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

0306090120JanFebMarAprMayJunJulAugSepOctNovDecUnhealthyPoorUnhealthyMar 1391 µg/m³Jul 2246 µg/m³
PM2.5 (µg/m³)Level
Jan83Unhealthy
Feb85Unhealthy
Mar92Unhealthy
Apr75Unhealthy
May62Unhealthy
Jun57Unhealthy
Jul46Poor
Aug47Poor
Sep61Unhealthy
Oct74Unhealthy
Nov79Unhealthy
Dec73Unhealthy
Location & terrain

Where is Yesan?

Yesan sits at 36.7°N, 126.8°E, 23 m above sea level, in South Korea. The nearest listed city is Hongseong, 18 km away.

GongjuSeosanSeonghwanSejong

Topography around Yesan

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

Within 3 km, the terrain around Yesan has significant variations in elevation — a maximum elevation change of 402 m around an average of 84 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 615 m; within 80 km, large variations in elevation — a maximum elevation change of 882 m.

The land around Yesan is covered by trees (57%) within 3 km, trees (49%) and cropland (36%) within 16 km, and trees (41%), water (27%) and cropland (21%) within 80 km.

3 km
402 m
16 km
615 m
80 km
882 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Hongseong 18 km · Asan 19 km · Tangjin 31 km · Cheonan 31 km · Gongju 35 km · Seosan 37 km · Seonghwan 37 km · Sejong 41 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 Yesan (36.6776°, 126.8427°, elevation 23 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).