Osan in Summer
In summer (June, July and August), Osan sees average daytime highs around 28°C and overnight lows near 21°C, with 628 mm of rain over about 37 wet days across the season. It is the warmest season of the year and the wettest season of the year.
Over the season highs climb from about 25°C in early June to 28°C by late August. The sky is clear or mostly clear about 27% of the time across summer, and the air most often feels oppressive.
Summer is Osan's 2nd-best season to visit on our travel score. For the whole year in context, see Osan's year-round climate.
- Avg daytime high
- 28°C
- warmest season of the year
- Avg overnight low
- 21°C
- Rainfall
- 628 mm
- 37 wet days
- Avg wind
- 9 km/h
- Travel score
- 5.6
- 2nd-best season
- Months
- Jun · Jul · Aug
Temperature in Osan in Summer
Over the season highs climb from about 25°C in early June to 28°C by late August.
A typical summer day in Osan reaches about 28°C and drops to 21°C overnight. The warmest of the three months is August, the coolest June.
How summer really feels in Osan
Once humidity and wind are folded in, summer brings about 28 days that feel above 32°C and 0 that feel at or below 0°C.
The story in summer is heat — humidity pushes the afternoon "feels like" well above the raw temperature.
Osan weather by month
How the three summer months (June, July and August) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 2° / -6° | 21 | 3.8 | 2.3 | 9.7 | 0.0 |
| Feb | 5° / -4° | 27 | 4.1 | 1.7 | 10.6 | 0.3 |
| Mar | 11° / 1° | 39 | 6.1 | 1 | 11.7 | 2.9 |
| Apr | 17° / 6° | 69 | 7.1 | 0 | 12.9 | 5.9 |
| May | 23° / 12° | 88 | 7.1 | 0 | 14 | 7.3 |
| Jun | 26° / 18° | 118 | 7.6 | 0 | 14.5 | 6.8 |
| Jul | 28° / 22° | 279 | 15.3 | 0 | 14.3 | 5.1 |
| Aug | 29° / 22° | 231 | 14 | 0 | 13.4 | 5.0 |
| Sep | 26° / 17° | 124 | 7.8 | 0 | 12.3 | 7.0 |
| Oct | 20° / 10° | 55 | 5.2 | 0 | 11 | 7.2 |
| Nov | 12° / 3° | 47 | 7.3 | 0.3 | 10 | 3.5 |
| Dec | 5° / -4° | 23 | 5.1 | 1.6 | 9.5 | 0.2 |
Cloud cover in Summer
The sky is clear or mostly clear about 27% of the time across summer.
Chance of precipitation in Summer
Osan gets around 628 mm of rain over 37 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 9 km/h across summer.
Sunrise & sunset in Summer
Daylight runs from about 14 h 24 min in early June to 12 h 54 min by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 4.8 kWh/m².
Hazard calendar for Osan
In summer, Osan overlaps its pacific typhoon and rainy season 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.
Is summer a good time to visit Osan?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is a reasonable time to visit Osan for sightseeing. The water and warmth also suit a beach or pool day.
What to pack for Osan in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Osan sees daytime highs around 28°C and nights near 21°C. Pack light clothes and rain gear. Worth having: sun protection. About 37 days see rain.
Sea temperature near Osan in Summer
The nearest coast averages about 20°C across summer — 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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 6 | 4 | 5 | 8 | 12 | 16 | 21 | 23 | 23 | 20 | 15 | 10 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Cool | Refreshing | Refreshing | Refreshing | Cool | Cool | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 6 | Bracing |
| Feb | 4 | Bracing |
| Mar | 5 | Bracing |
| Apr | 8 | Bracing |
| May | 12 | Bracing |
| Jun | 16 | Cool |
| Jul | 21 | Refreshing |
| Aug | 23 | Refreshing |
| Sep | 23 | Refreshing |
| Oct | 20 | Cool |
| Nov | 15 | Cool |
| Dec | 10 | Bracing |
UV index in Osan in Summer
Clear-sky midday UV across summer averages around 8 — 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.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 2 | 3 | 4 | 6 | 6 | 7 | 8 | 8 | 7 | 5 | 3 | 2 |
| Level | Low | Moderate | Moderate | High | High | High | Very high | Very high | Very high | Moderate | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Low |
| Feb | 3 | Moderate |
| Mar | 4 | Moderate |
| Apr | 6 | High |
| May | 6 | High |
| Jun | 7 | High |
| Jul | 8 | Very high |
| Aug | 8 | Very high |
| Sep | 7 | Very high |
| Oct | 5 | Moderate |
| Nov | 3 | Moderate |
| Dec | 2 | Low |
Air quality in Osan in Summer
Average fine-particle pollution (PM2.5) through the year — so you can see where summer 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).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 145 | 149 | 160 | 127 | 111 | 98 | 88 | 81 | 110 | 132 | 142 | 133 |
| Level | Unhealthy | Unhealthy | Very unhealthy | Unhealthy | Unhealthy | Unhealthy | Unhealthy | Unhealthy | Unhealthy | Unhealthy | Unhealthy | Unhealthy |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 145 | Unhealthy |
| Feb | 149 | Unhealthy |
| Mar | 160 | Very unhealthy |
| Apr | 127 | Unhealthy |
| May | 111 | Unhealthy |
| Jun | 98 | Unhealthy |
| Jul | 88 | Unhealthy |
| Aug | 81 | Unhealthy |
| Sep | 110 | Unhealthy |
| Oct | 132 | Unhealthy |
| Nov | 142 | Unhealthy |
| Dec | 133 | Unhealthy |
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.
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
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.