Osan in Fall
In fall (September, October and November), Osan sees average daytime highs around 19°C and overnight lows near 10°C, with 226 mm of precipitation over about 20 wet days across the season. It is the 2nd-warmest season and the 2nd-wettest season.
Over the season highs ease from about 27°C in early September to 8°C by late November. The sky is clear or mostly clear about 45% of the time across fall, and the air most often feels dry.
Fall is Osan's best season of the year to visit on our travel score. For the whole year in context, see Osan's year-round climate.
- Avg daytime high
- 19°C
- 2nd-warmest season
- Avg overnight low
- 10°C
- Precipitation
- 226 mm
- 20 wet days
- Avg wind
- 9 km/h
- Travel score
- 5.9
- best season of the year
- Months
- Sep · Oct · Nov
Temperature in Osan in Fall
Over the season highs ease from about 27°C in early September to 8°C by late November.
A typical fall day in Osan reaches about 19°C and drops to 10°C overnight. The warmest of the three months is September, the coolest November.
How fall really feels in Osan
Once humidity and wind are folded in, fall brings about 0 days that feel above 32°C and 15 that feel at or below 0°C.
The story in fall is cold — wind chill drags the overnight "feels like" below the raw low.
Osan weather by month
How the three fall months (September, October and November) 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 Fall
The sky is clear or mostly clear about 45% of the time across fall.
Chance of precipitation in Fall
Osan gets around 226 mm of rain and snow over 20 wet days across fall. The line is the day-by-day chance of measurable precipitation.
Humidity in Fall
Most of fall feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Fall
Winds average 9 km/h across fall.
Sunrise & sunset in Fall
Daylight runs from about 12 h 48 min in early September to 9 h 42 min by late November. The lit band spans sunrise to sunset each day.
Solar energy in Fall
Average shortwave solar energy reaching the ground each day across fall, about 3.5 kWh/m².
Hazard calendar for Osan
In fall, Osan overlaps 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.
Is fall a good time to visit Osan?
Our two travel scores rate fall for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
fall is a reasonable time to visit Osan for sightseeing.
What to pack for Osan in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, Osan sees daytime highs around 19°C and nights near 10°C. Pack a warm layer. Worth having: light clothes. About 20 days see rain.
Sea temperature near Osan in Fall
The nearest coast averages about 19°C across fall — 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 Fall
Clear-sky midday UV across fall averages around 5 — 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 Fall
Average fine-particle pollution (PM2.5) through the year — so you can see where fall 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.