Osan Temperature by Month
The average annual maximum temperature in Osan, Gyeonggi-do, South Korea is 19°C (66°F), with daytime highs ranging from 4°C (39°F) in January to 31°C (88°F) in August. This page covers monthly averages, day-night differences, and how Osan compares to cities worldwide.
Osan Monthly Temperatures
In Osan, temperatures differ significantly between summer and winter months. Nighttime lows reflect this range, dropping from 23°C (73°F) in August to -6°C (21°F) in January.
The chart below illustrates the average maximum day and minimum night temperatures in Osan by month:
The minimum temperature is often recorded between 4 AM and 6 AM, while the highest temperature is usually reached at 3 PM, when the sun's heating effect is strongest. August, the warmest month, gets 209 hours of sunshine.
The chart below shows the average temperature throughout the year:
Temperature: Osan vs South Korea
The map below shows the annual temperature across South Korea. You can also select individual months if you want to compare a specific time of year.
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Osan vs World: Temperature Compared
Osan's average annual maximum temperature is 19°C (66°F). To put that in context, here's how it compares to a few well-known destinations:
Lisbon, Portugal averages 21°C (70°F) annually — warm summers, mild winters, and rain mainly in the cooler months.
Queenstown, New Zealand averages 10°C (50°F) annually — remember seasons are flipped, so its coldest months fall in June and July.
Boston, USA averages 16°C (61°F) annually, with four distinct seasons and cold winters that rival northern Europe.
Melbourne, Australia averages 20°C (68°F) annually — known for unpredictable weather, with four seasons sometimes happening in one day.
What Does the Temperature Feel Like in Osan?
Temperature alone doesn't tell the whole story — humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.
In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.
In Osan, January is the coolest month, with average highs of 4°C (39°F) and humidity around 71% — considered high. In August, the warmest month, temperatures average 31°C (88°F) with 78% humidity — conditions that feel high. For a full picture, see our humidity page.
Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.
The readings come from a range of sources — land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.
For cities and regions with significant elevation, altitude is one of the biggest factors shaping local temperatures. As a rule of thumb, temperatures fall by around 6°C for every 1,000 metres gained — so a city at 2,000 metres will typically be around 12°C cooler than a city at sea level in the same region. Higher ground also tends to see more dramatic day-to-night temperature swings, since thinner air loses heat faster after sunset.
For more on Osan's weather — including monthly rainfall, sunshine hours, and humidity — visit our Osan climate page.
