Osan weather in April

In April, Osan sees average daytime highs of 17°C and overnight lows near 6°C, with 69 mm of rain across 7.1 wet days and about 12.9 hours of daylight. It is the 7th-warmest and 6th-wettest month of the year here.

Highs climb over the month, from about 14°C in the first days to 20°C by the end. The sky is clear or mostly clear about 43% of the time in April, and the air most often feels dry.

Daylight stretches from about 12 h 24 min at the start of April to 13 h 30 min by month's end. Set against the rest of the year, April is Osan's 7th-clearest and 2nd-windiest month. For the whole year in context, see Osan's year-round climate.

Daytime high
17°
7th warmest
Overnight low
6th coldest
Rainfall
69 mm
7.1 wet days
Daylight
13 hours
6:03 AM – 7:01 PM
Cloud cover
50%
7th clearest
Wind
11 km/h
2nd windiest
Solar energy
5.46 kWh/m²
Travel score
5.9
out of 10

Osan is city of Gyeonggi-do, South Korea.

Density
5,584/km²
people per km²

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

Temperature in April

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 14°C in the first days to 20°C by the end.

A typical April day in Osan reaches about 17°C in the afternoon and slips back to 6°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 12°C and 23°C. Set against its neighbours, April runs about 7°C warmer than March and about 5°C cooler than May.

10°20°30°151015202530
Avg high (°C)Avg low (°C)
1144
2144
3144
4154
5154
6155
7155
8165
9165
10165
11166
12176
13176
14176
15176
16177
17187
18187
19187
20187
21198
22198
23198
24198
25198
26209
27209
28209
29209
302010

How April really feels in Osan

Once humidity and wind are folded in, April 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

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

Osan weather by month

How April compares with the rest of the year at a glance. April is the 7th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -6°213.82.39.70.0
Feb / -4°274.11.710.60.3
Mar11° / 396.1111.72.9
Apr17° / 697.1012.95.9
May23° / 12°887.10147.3
Jun26° / 18°1187.6014.56.8
Jul28° / 22°27915.3014.35.1
Aug29° / 22°23114013.45.0
Sep26° / 17°1247.8012.37.0
Oct20° / 10°555.20117.2
Nov12° / 477.30.3103.5
Dec / -4°235.11.69.50.2

Cloud cover in April

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 43% of the time in April.

Beyond those clear spells, partly cloudy skies cover about 14% of April, with mostly cloudy or overcast conditions the remaining 44%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15941
25842
35842
45842
55842
65842
75842
85842
95842
105743
115743
125743
135743
145743
155644
165644
175644
185644
195644
205644
215644
225545
235644
245545
255545
265446
275446
285545
295545
305446

Chance of precipitation in April

Any precipitation

Osan gets around 69 mm of rain over 7.1 wet days in April. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 23% and peaks near 25% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
121
221
321
421
522
622
722
822
922
1023
1123
1223
1323
1423
1524
1624
1724
1824
1924
2024
2124
2224
2324
2425
2525
2625
2725
2825
2924
3024

Humidity in April

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, April lands in the dry band about 97% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
110000
210000
310000
410000
510000
69910
79910
89910
99910
109910
119910
129910
139910
149820
159820
169820
179820
189820
199820
209631
219631
229541
239541
249451
259451
269361
279172
289082
299082
308992

Wind in April

Winds average 11 km/h in April.

Across April, daily wind ranges from about 11 km/h on the calmest days to 11 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
111calm
211calm
311calm
411calm
511calm
611calm
711calm
811calm
911calm
1011calm
1111calm
1211calm
1311calm
1411calm
1511calm
1611calm
1711calm
1811calm
1911calm
2011calm
2111calm
2211calm
2311calm
2411calm
2511calm
2611calm
2711calm
2811calm
2911calm
3011calm

Sunrise & sunset in April

DaylightNight

Daylight runs from about 12 h 24 min at the start of April to 13 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 66 minutes over April. Sunrise moves from 6:26 AM to 5:45 AM, and sunset from 6:47 PM to 7:13 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.46:266:47
212.46:246:48
312.46:236:49
412.56:216:50
512.56:206:51
612.66:186:52
712.66:176:52
812.66:156:53
912.76:146:54
1012.76:126:55
1112.86:116:56
1212.86:096:57
1312.86:086:58
1412.96:066:59
1512.96:057:00
1613.06:037:01
1713.06:027:01
1813.06:017:02
1913.15:597:03
2013.15:587:04
2113.15:567:05
2213.25:557:06
2313.25:547:07
2413.35:527:08
2513.35:517:09
2613.35:507:10
2713.45:497:10
2813.45:477:11
2913.45:467:12
3013.55:457:13

Solar energy in April

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in April, about 5.46 kWh/m².

For context, solar energy here swings from a low near 2.31 kWh/m² to a high of 5.85 kWh/m² in May across the year — April's 5.46 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.3Bright
45.3Bright
55.3Bright
65.3Bright
75.3Bright
85.3Bright
95.4Bright
105.4Bright
115.4Bright
125.4Bright
135.5Bright
145.5Bright
155.5Bright
165.5Bright
175.5Bright
185.5Bright
195.5Bright
205.5Bright
215.5Bright
225.6Bright
235.6Bright
245.6Bright
255.6Bright
265.6Bright
275.6Bright
285.6Bright
295.6Bright
305.6Bright
Planning a trip in April

Hazard calendar for Osan

In seasonPeak

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

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

Osan'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 April a good time to visit Osan?

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

5.9
Sightseeing
5th-best month of the year
1.7
Beach & pool
7th-best month of the year

April is a reasonable time to visit Osan for sightseeing.

What to pack for Osan in April

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

In April, Osan sees daytime highs around 17°C and nights near 6°C. Worth packing: a warm layer and sun protection. About 7 days see rain.

a warm layersun protection

Sea temperature near Osan in April

The nearest coast averages about 8°C in April — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 40 km away) is warmest in August at about 23°C and coldest in February near 4°C.

It's comfortable for a long swim from Jul 12 to Oct 14 — 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
Jun16Cool
Jul21Refreshing
Aug23Refreshing
Sep23Refreshing
Oct20Cool
Nov15Cool
Dec10Bracing

UV index in Osan in April

LowModerateHighVery highExtreme

Clear-sky midday UV in April peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Osan peaks around August 11 at about 8 (very high) — sunscreen, a hat and midday shade are essential. 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 highHighModerateAug 11UV 8Dec 23UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May6High
Jun7High
Jul8Very high
Aug8Very high
Sep7Very high
Oct5Moderate
Nov3Moderate
Dec2Low

Air quality in Osan in April

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Osan 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 Osan?

Osan sits at 37.2°N, 127.1°E, 22 m above sea level, in South Korea. The nearest listed city is Suwon, 16 km away.

Topography around Osan

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

Within 3 km, the terrain around Osan has only modest variations in elevation — a maximum elevation change of 138 m around an average of 39 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 496 m; within 80 km, large variations in elevation — a maximum elevation change of 1,126 m.

The land around Osan is covered by artificial surfaces (48%) and trees (25%) within 3 km, trees (39%) and artificial surfaces (32%) within 16 km, and trees (49%) within 80 km.

3 km
138 m
16 km
496 m
80 km
1,126 m
treesgrasslandcroplandartificial surfacesbare terrainwater
April weather nearby: Suwon 16 km · Pyeongtaek 18 km · Hwaseong-si 23 km · Anseong 24 km · Uiwang 26 km · Gunpo 26 km · Seonghwan 27 km · Ansan 29 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 Osan (37.1522°, 127.0706°, elevation 22 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).