Goyang-si weather in September

In September, Goyang-si sees average daytime highs of 26°C and overnight lows near 17°C, with 120 mm of rain across 7.9 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 27°C in the first days to 24°C by the end. The sky is clear or mostly clear about 38% of the time in September, and the air most often feels humid.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Goyang-si's 9th-clearest and 12th-windiest month. For the whole year in context, see Goyang-si's year-round climate.

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

Goyang-si is city in Gyeonggi Province, South Korea.

Density
3,972/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 27°C in the first days to 24°C by the end.

A typical September day in Goyang-si 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°20°30°151015202530
Avg high (°C)Avg low (°C)
12820
22820
32719
42719
52719
62719
72719
82718
92718
102718
112618
122618
132617
142617
152617
162617
172616
182516
192516
202516
212515
222515
232515
242415
252414
262414
272414
282414
292313
302313

How September really feels in Goyang-si

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.

Goyang-si weather by month

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

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -7°183.52.39.70.0
Feb / -5°233.91.710.50.3
Mar11° / 355.70.911.72.9
Apr17° / 667.20.112.95.9
May23° / 13°9980147.2
Jun27° / 18°1259014.66.6
Jul28° / 22°31316.3014.34.9
Aug29° / 22°26414.9013.54.7
Sep26° / 17°1207.9012.37.0
Oct20° / 525.30117.1
Nov11° / 4770.3103.2
Dec / -5°224.81.69.40.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 38% 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 48%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14654
24654
34753
44753
54852
64852
74852
84951
94951
104951
115050
125149
135149
145248
155248
165347
175347
185446
195446
205545
215545
225545
235644
245644
255644
265644
275644
285644
295743
305743

Chance of precipitation in September

Any precipitation

Goyang-si gets around 120 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 40% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
140
239
338
437
536
634
733
832
931
1030
1129
1228
1328
1427
1526
1625
1724
1824
1923
2022
2122
2222
2321
2421
2521
2621
2721
2820
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 26% of days. Sticky, muggy-or-worse air turns up on roughly 32% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1172339273
2182539252
3292638232
42102738211
53112837201
63132937181
74143036161
85153035140
96173034130
107183133110
118203132100
12922313080
131123302870
141225302760
151427292550
161528292350
171730282140
181931272030
192032271830
202233261620
212434261420
222635251310
232836241110
243036231010
25323722810
26343721710
27373720600
28393619500
29423618500
30453517400

Wind in September

Winds average 8 km/h in September, the calmest month.

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.

0246810151015202530
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 54 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 72 minutes over September. Sunrise moves from 6:07 AM to 6:32 AM, and sunset from 6:58 PM to 6:12 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.96:076:58
212.86:086:56
312.86:096:55
412.76:096:53
512.76:106:52
612.66:116:50
712.66:126:49
812.66:136:47
912.56:146:45
1012.56:156:44
1112.46:156:42
1212.46:166:41
1312.46:176:39
1412.36:186:37
1512.36:196:36
1612.26:206:34
1712.26:216:33
1812.26:226:31
1912.16:226:29
2012.16:236:28
2112.06:246:26
2212.06:256:24
2311.96:266:23
2411.96:276:21
2511.96:286:20
2611.86:296:18
2711.86:306:16
2811.76:306:15
2911.76:316:13
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 4.29 kWh/m².

For context, solar energy here swings from a low near 2.35 kWh/m² to a high of 5.79 kWh/m² in May across the year — September's 4.29 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.3Bright
24.3Bright
34.3Bright
44.3Bright
54.3Bright
64.3Bright
74.3Bright
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
214.2Bright
224.2Bright
234.2Bright
244.2Bright
254.2Bright
264.1Bright
274.1Bright
284.1Bright
294.1Bright
304.1Bright
Planning a trip in September

Hazard calendar for Goyang-si

In seasonPeak

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

Goyang-si sits in the Pacific typhoon belt; the season peaks July–October.

Goyang-si's rainy season runs July–August, 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 Goyang-si?

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 Goyang-si for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Goyang-si in September

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

In September, Goyang-si 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 Goyang-si 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 36 km away) is warmest in August at about 24°C and coldest in February near 4°C.

It's comfortable for a long swim from Jul 11 to Oct 13 — about 3.1 months when the water holds above 20°C.

0°10°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan6Bracing
Feb4Bracing
Mar5Bracing
Apr8Bracing
May12Bracing
Jun17Cool
Jul21Refreshing
Aug24Refreshing
Sep23Refreshing
Oct20Cool
Nov15Bracing
Dec10Bracing

UV index in Goyang-si 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 Goyang-si peaks around July 22 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 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateJul 22UV 8Dec 23UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May5High
Jun7High
Jul8Very high
Aug8Very high
Sep7High
Oct5Moderate
Nov3Moderate
Dec2Low

Air quality in Goyang-si 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 Goyang-si is worst in March — around 160 µg/m³ PM2.5 (very unhealthy), about 2.0× the cleanest month (August, 81 µg/m³).

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

0306090120150180JanFebMarAprMayJunJulAugSepOctNovDecUnhealthyVery unhealthyUnhealthyMar 13158 µg/m³Aug 1282 µg/m³
PM2.5 (µg/m³)Level
Jan145Unhealthy
Feb149Unhealthy
Mar160Very unhealthy
Apr127Unhealthy
May111Unhealthy
Jun98Unhealthy
Jul88Unhealthy
Aug81Unhealthy
Sep110Unhealthy
Oct132Unhealthy
Nov142Unhealthy
Dec133Unhealthy
Location & terrain

Where is Goyang-si?

Goyang-si sits at 37.7°N, 126.8°E, 19 m above sea level, in South Korea. The nearest listed city is Gimpo-si, 11 km away.

Topography around Goyang-si

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

Within 3 km, the terrain around Goyang-si has only modest variations in elevation — a maximum elevation change of 98 m around an average of 33 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 778 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,443 m.

The land around Goyang-si is covered by trees (41%) and artificial surfaces (36%) within 3 km, trees (39%) and artificial surfaces (36%) within 16 km, and trees (43%) and water (22%) within 80 km.

3 km
98 m
16 km
778 m
80 km
1,443 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Gimpo-si 11 km · Seoul 16 km · Bucheon-si 18 km · Gwangmyeong 20 km · Uijeongbu-si 21 km · Munsan 23 km · Siheungdong 24 km · Incheon 25 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 Goyang-si (37.6564°, 126.835°, 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).