Seosan weather in December

In December, Seosan sees average daytime highs of 6°C and overnight lows near -0°C, with 26 mm of precipitation across 6.1 wet days and about 9.5 hours of daylight. It is the 10th-warmest and 11th-wettest month of the year here.

Highs ease over the month, from about 8°C in the first days to 4°C by the end. The sky is clear or mostly clear about 26% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 42 min at the start of December to 9 h 30 min by month's end. Set against the rest of the year, December is Seosan's 9th-clearest and 1st-windiest month. For the whole year in context, see Seosan's year-round climate.

Daytime high
10th warmest
Overnight low
-0°
3rd coldest
Precipitation
26 mm
6.1 wet days
Daylight
9 h 30 min
7:46 AM – 5:15 PM
Cloud cover
62%
9th clearest
Wind
14 km/h
1st windiest
Solar energy
2.15 kWh/m²
Travel score
0.4
out of 10

Seosan is city in South Korea.

Density
100/km²
people per km²

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 8°C in the first days to 4°C by the end.

A typical December day in Seosan reaches about 6°C in the afternoon and slips back to -0°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 0°C and 11°C. Set against its neighbours, December runs about 7°C cooler than November and about 3°C warmer than January.

-10°-5°10°15°151015202531
Avg high (°C)Avg low (°C)
182
282
382
481
571
671
771
871
970
1060
1160
1260
1360
1460
1560
165-1
175-1
185-1
195-1
205-1
215-1
225-1
235-1
245-1
254-1
264-1
274-2
284-2
294-2
304-2
314-2

How December really feels in Seosan

Once humidity and wind are folded in, December averages 0 days that feel above 32°C and 31 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
31
wind chill below the day's low

The story in December is cold — wind chill drags the overnight "feels like" below the raw low.

Seosan weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -3°224.949.80.0
Feb / -2°274.21.710.60.2
Mar10° / 415.60.911.72.4
Apr16° / 696.8012.95.3
May21° / 13°797013.97.0
Jun25° / 18°1167.7014.57.1
Jul27° / 22°24514.8014.35.4
Aug29° / 23°22513.7013.45.3
Sep25° / 18°1337.5012.27.2
Oct20° / 12°555.30117.1
Nov12° / 497.20.4103.6
Dec / -0°266.13.49.50.4

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 26% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 17% of December, with mostly cloudy or overcast conditions the remaining 57%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14753
24753
34654
44654
54555
64357
74456
84357
94258
104159
114159
124159
134159
144159
154159
164159
174357
184357
194258
204357
214357
224357
234456
244357
254357
264357
274258
284258
294258
304159
314159

Chance of precipitation in December

Any precipitationSnow

Seosan gets around 26 mm of rain and snow over 6.1 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 20% and peaks near 24% on the wettest days, and about 3 days bring snow. The odds ease toward the end of the month.

0%10%20%30%151015202531
Rain chance (%)Snow chance (%)
1246
2247
3247
4248
5238
6239
7239
82310
92310
102210
112210
122111
132111
142011
151911
161911
171811
181811
191711
201711
211711
221711
231712
241712
251712
261712
271713
281713
291713
301713
311713

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

Wind in December

Winds average 14 km/h in December, the windiest month of the year.

Across December, daily wind ranges from about 13 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
714light breeze
814light breeze
914light breeze
1014light breeze
1114light breeze
1214light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1714light breeze
1814light breeze
1914light breeze
2014light breeze
2114light breeze
2214light breeze
2314light breeze
2414light breeze
2514light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze
3114light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 42 min at the start of December to 9 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:34 AM to 7:52 AM, and sunset from 5:14 PM to 5:23 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.77:345:14
29.67:355:14
39.67:365:14
49.67:375:14
59.67:375:14
69.67:385:14
79.67:395:14
89.67:405:14
99.67:415:14
109.57:415:14
119.57:425:14
129.57:435:14
139.57:445:14
149.57:445:15
159.57:455:15
169.57:465:15
179.57:465:15
189.57:475:16
199.57:475:16
209.57:485:17
219.57:485:17
229.57:495:18
239.57:495:18
249.57:505:19
259.57:505:19
269.57:505:20
279.57:515:20
289.57:515:21
299.57:515:21
309.57:525:22
319.57:525:23

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 2.15 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 2.15 kWh/m² to a high of 5.95 kWh/m² in May across the year — December's 2.15 kWh/m² sits near the bottom.

0123151015202531
Solar energy (kWh/m²)Level
12.2Moderate
22.2Moderate
32.2Moderate
42.2Moderate
52.2Moderate
62.2Moderate
72.1Moderate
82.1Moderate
92.1Moderate
102.1Moderate
112.1Moderate
122.1Moderate
132.1Moderate
142.1Moderate
152.1Moderate
162.1Moderate
172.1Moderate
182.1Moderate
192.1Moderate
202.2Moderate
212.2Moderate
222.2Moderate
232.2Moderate
242.2Moderate
252.2Moderate
262.2Moderate
272.2Moderate
282.2Moderate
292.2Moderate
302.2Moderate
312.2Moderate
Planning a trip in December

Hazard calendar for Seosan

In seasonPeak

In December, Seosan sits inside its pacific typhoon season. The full year is below, with each hazard's peak months called out.

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

Seosan'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 December a good time to visit Seosan?

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

0.4
Sightseeing
10th-best month of the year
0.0
Beach & pool
10th-best month of the year

December is a weaker month for outdoor sightseeing in Seosan.

What to pack for Seosan in December

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

In December, Seosan sees daytime highs around 6°C and nights near -0°C. Pack a warm layer. Worth having: a heavy coat. About 6 days see rain.

a warm layera heavy coat

Sea temperature near Seosan in December

The nearest coast averages about 11°C in December — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 19 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 Seosan in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 2. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Seosan peaks around July 20 at about 7 (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 20UV 7Dec 23UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May6High
Jun7High
Jul8Very high
Aug7Very high
Sep7Very high
Oct5High
Nov3Moderate
Dec2Low

Air quality in Seosan in December

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Seosan 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 Seosan?

Seosan sits at 36.8°N, 126.5°E, 33 m above sea level, in South Korea. The nearest listed city is Tangjin, 20 km away.

YesanAsanBoryeongHwaseong-siPyeongtaek

Topography around Seosan

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

Within 3 km, the terrain around Seosan has only modest variations in elevation — a maximum elevation change of 192 m around an average of 43 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 643 m; within 80 km, large variations in elevation — a maximum elevation change of 769 m.

The land around Seosan is covered by cropland (33%), trees (30%) and artificial surfaces (30%) within 3 km, cropland (39%) and trees (38%) within 16 km, and water (53%) and trees (25%) within 80 km.

3 km
192 m
16 km
643 m
80 km
769 m
treesgrasslandcroplandartificial surfaceswaterwetland
December weather nearby: Tangjin 20 km · Taesal-li 21 km · Hongseong 28 km · Yesan 37 km · Asan 49 km · Boryeong 50 km · Hwaseong-si 57 km · Pyeongtaek 61 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 Seosan (36.7817°, 126.4522°, elevation 33 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).