Climate averages 1991–2020
Osan weather
in May.
A warm, moderately wet month: the 5th warmest and the 8th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
May is a warm month in Osan: daytime highs average 22.2°C and nights cool to about 11.6°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 88 mm of rain on roughly 7 days, which makes May a moderately wet month (the 8th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 14 h 08 min on an average May day.
The nearest other city in this atlas is Suwon (16 km away). In May its highs average 21.6°C, 0.6°C cooler than Osan, with 88 mm of rain.
Among the 79 cities listed in South Korea, Osan ranks joint 37th of 79 for the warmest May highs and joint 16th of 79 for the driest May (rainfall, lowest first). The mean May high of those 79 cities is 21.9°C; Osan is 0.3°C warmer than that mean.
From May to June, average highs rise by 4.2°C to 26.5°C, and monthly rainfall rises from 88 mm to 118 mm.
The annual picture
May 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 | 16.8°C5.7°C | 5.7°C | 69 | 7.1 | 13.113 h |
| May, selected | 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
May in nearby cities
- Suwon in MaySouth Korea · 16 kmHigh 21.6°C · Low 11.3°C · 88 mm rain
- Pyeongtaek in MaySouth Korea · 18 kmHigh 22.9°C · Low 12.0°C · 84 mm rain
- Hwaseong-si in MaySouth Korea · 23 kmHigh 19.1°C · Low 12.0°C · 104 mm rain
- Ansan-si in MaySouth Korea · 29 kmHigh 20.5°C · Low 11.9°C · 104 mm rain
- Anyang-si in MaySouth Korea · 30 kmHigh 20.7°C · Low 11.7°C · 96 mm rain
- Seongnam-si in MaySouth Korea · 32 kmHigh 21.8°C · Low 11.3°C · 104 mm rain
- Gwangju, South Korea in MaySouth Korea · 33 kmHigh 22.6°C · Low 11.6°C · 104 mm rain
- Icheon-si in MaySouth Korea · 36 kmHigh 22.6°C · Low 11.4°C · 98 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.