Climate averages 1991–2020
Osan weather
in April.
A mild, moderately wet month: the 7th warmest and the 7th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
April is a mild month in Osan: daytime highs average 16.8°C and nights cool to about 5.7°C. By daytime temperature it is the 7th warmest of the 12 months.
Expect about 69 mm of rain on roughly 7 days, which makes April a moderately wet month (the 7th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 07 min on an average April day.
The nearest other city in this atlas is Suwon (16 km away). In April its highs average 16.2°C, 0.5°C cooler than Osan, with 69 mm of rain.
Among the 79 cities listed in South Korea, Osan ranks joint 45th of 79 for the warmest April highs and joint 8th of 79 for the driest April (rainfall, lowest first). The mean April high of those 79 cities is 16.9°C; Osan is 0.1°C cooler than that mean.
From April to May, average highs rise by 5.5°C to 22.2°C, and monthly rainfall rises from 69 mm to 88 mm.
The annual picture
April in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Osan climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 2.2°C-5.5°C | -5.5°C | 20 | 3.8 | 9.910 h |
| February | 4.9°C-3.8°C | -3.8°C | 27 | 4.1 | 10.811 h |
| March | 10.2°C0.1°C | 0.1°C | 39 | 6.1 | 11.912 h |
| April, selected | 16.8°C5.7°C | 5.7°C | 69 | 7.1 | 13.113 h |
| May | 22.2°C11.6°C | 11.6°C | 88 | 7.1 | 14.114 h |
| June | 26.5°C17.1°C | 17.1°C | 118 | 7.6 | 14.715 h |
| July | 28.2°C21.6°C | 21.6°C | 279 | 15.3 | 14.414 h |
| August | 28.8°C22.3°C | 22.3°C | 231 | 14.0 | 13.614 h |
| September | 24.8°C16.9°C | 16.9°C | 124 | 7.8 | 12.512 h |
| October | 18.9°C9.7°C | 9.7°C | 55 | 5.2 | 11.311 h |
| November | 11.3°C2.6°C | 2.6°C | 47 | 7.3 | 10.210 h |
| December | 4.2°C-3.6°C | -3.6°C | 23 | 5.1 | 9.710 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
April in nearby cities
- Suwon in AprilSouth Korea · 16 kmHigh 16.2°C · Low 5.4°C · 69 mm rain
- Pyeongtaek in AprilSouth Korea · 18 kmHigh 17.3°C · Low 6.0°C · 68 mm rain
- Hwaseong-si in AprilSouth Korea · 23 kmHigh 14.0°C · Low 6.6°C · 79 mm rain
- Ansan-si in AprilSouth Korea · 29 kmHigh 15.3°C · Low 6.2°C · 79 mm rain
- Anyang-si in AprilSouth Korea · 30 kmHigh 15.5°C · Low 5.9°C · 70 mm rain
- Seongnam-si in AprilSouth Korea · 32 kmHigh 16.4°C · Low 5.4°C · 79 mm rain
- Gwangju, South Korea in AprilSouth Korea · 33 kmHigh 17.1°C · Low 5.7°C · 79 mm rain
- Icheon-si in AprilSouth Korea · 36 kmHigh 17.1°C · Low 5.4°C · 81 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Osan) is explained once on the Osan year overview and on the Sources, method and limits page.
Suwon lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.