nomadseason

Monthly climate in Osan, South Korea

Last updated: July 31, 2025

Under the Köppen–Geiger climate classification Osan features a humid continental climate (Dwa). Temperatures typically range between -2 °C (29 °F) and 27 °C (80 °F) through the year, but rarely can drop to -17 °C (2 °F) or can rise to as high as 38 °C (101 °F). The average annual precipitation amounts to about 1093 mm (43.0 inches) and receives 83 rainy days on the 1 mm (0.04 inches) threshold annually. Osan enjoys an average of 3222 hours of sunshine throughout the year, and daylight varies from 9 hours 37 minutes to 14 hours 40 minutes per day.

Monthly average temperatures in Osan, South Korea

The warmest months in Osan are June, July and August, with daily mean temperatures ranging from 22 to 27 °C (72 - 80 °F) throughout the day. The coldest temperatures usually occur in January, February and December, when daily mean temperatures range from -2 to 0 °C (29 - 33 °F) throughout the day. On average each year, Osan experiences 94 days above 25 °C (77.0 °F) and 90 days below 0 °C (32.0 °F).

Monthly average temperatures with daily means, minimums and maximums for period, average high and low temperatures in Osan. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to June 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Maximum13°C
(55°F)		18°C
(65°F)		21°C
(70°F)		28°C
(82°F)		31°C
(89°F)		33°C
(91°F)		36°C
(98°F)		38°C
(101°F)		31°C
(88°F)		29°C
(84°F)		21°C
(70°F)		13°C
(56°F)
Mean maximum10°C
(50°F)		13°C
(56°F)		19°C
(66°F)		26°C
(78°F)		29°C
(85°F)		30°C
(87°F)		34°C
(94°F)		35°C
(95°F)		30°C
(85°F)		27°C
(80°F)		20°C
(68°F)		11°C
(53°F)
Average high3°C
(37°F)		5°C
(41°F)		12°C
(54°F)		18°C
(64°F)		23°C
(73°F)		27°C
(80°F)		29°C
(85°F)		30°C
(86°F)		26°C
(79°F)		20°C
(68°F)		13°C
(55°F)		5°C
(41°F)
Daily mean-2°C
(29°F)		0°C
(33°F)		7°C
(44°F)		12°C
(54°F)		18°C
(64°F)		22°C
(72°F)		26°C
(79°F)		27°C
(80°F)		22°C
(71°F)		15°C
(59°F)		8°C
(46°F)		0°C
(33°F)
Average low-6°C
(22°F)		-4°C
(25°F)		2°C
(36°F)		7°C
(45°F)		12°C
(55°F)		18°C
(64°F)		23°C
(73°F)		24°C
(75°F)		18°C
(64°F)		10°C
(51°F)		3°C
(37°F)		-4°C
(25°F)
Mean minimum-13°C
(9°F)		-11°C
(13°F)		-4°C
(25°F)		0°C
(32°F)		7°C
(46°F)		13°C
(56°F)		19°C
(66°F)		19°C
(67°F)		11°C
(52°F)		2°C
(37°F)		-4°C
(25°F)		-12°C
(11°F)
Minimum-17°C
(2°F)		-15°C
(4°F)		-6°C
(21°F)		-1°C
(30°F)		6°C
(42°F)		12°C
(53°F)		18°C
(65°F)		16°C
(61°F)		9°C
(48°F)		1°C
(33°F)		-5°C
(23°F)		-14°C
(8°F)

Compare climate in Osan with other places

Compare temperature, precipitation, sunshine, UV index in Osan, South Korea with other places around the world.

Monthly average precipitation in Osan, South Korea

Osan usually has the most precipitation in July, August and September, with an average of 12 rainy days and 209 mm (8.2 inches) of precipitation per month. The driest months in Osan are January, February and December. On average, 23 mm (0.9 inches) of precipitation falls during these months.

Monthly average precipitation and precipitation days in Osan. Generated using Copernicus Climate Change Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Average precipitation mm (inches)21 (0.8)23 (0.9)47 (1.9)54 (2.1)98 (3.9)80 (3.1)235 (9.3)255 (10.1)136 (5.4)62 (2.5)54 (2.1)26 (1.0)
Average precipitation days (≥ 1 mm)24558714149555

Monthly sunshine hours in Osan, South Korea

The sunniest months in Osan are May, June and July, when the sun shines an average of 10 hours 4 minutes a day. Least sunny months in Osan: January, November and December receive an average of 7 hours 13 minutes of sunshine daily.

Mean monthly sunshine duration, average sunshine hours per day and mean daily daylight hours in Osan. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2017 to January 2022.
 JanFebMarAprMayJunJulAugSepOctNovDec
Mean monthly sunshine hours198241282288315318293290261265231235
Mean daily daylight hours9h 53m10h 48m11h 57m13h 9m14h 9m14h 40m14h 24m13h 32m12h 23m11h 12m10h 9m9h 37m

Solar UV radiation in Osan, South Korea

Osan experiences the highest level of ultraviolet (UV) radiation in June, July and August, when the maximum UV index can reach values of 10 - 11, which corresponds to the Very High / Extreme category of sun exposure. January, February and December are in the Moderate exposure category. In these months, the maximum values of the UV index do not exceed 4. For more detailed information, check out our hourly Osan UV Index data.

Average daily maximum UV levels by month for Osan. Generated using Copernicus Atmosphere Monitoring Service information. Data for period from January 2022 to January 2023.
 JanFebMarAprMayJunJulAugSepOctNovDec
UV Index (month maximum)346891011119643