Climate averages 1991–2020
Asan weather
in September.
A warm, wet month: the 4th warmest and the 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Asan: daytime highs average 25.0°C and nights cool to about 17.1°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 137 mm of rain on roughly 8 days, which makes September a wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 27 min on an average September day.
The nearest other city in this atlas is Cheonan (13 km away). In September its highs average 25.2°C, about as warm as Asan, with 139 mm of rain.
Among the 79 cities listed in South Korea, Asan ranks joint 28th of 79 for the warmest September highs and joint 33rd of 79 for the driest September (rainfall, lowest first). The mean September high of those 79 cities is 24.8°C; Asan is 0.2°C warmer than that mean.
From September to October, average highs fall by 5.8°C to 19.1°C, and monthly rainfall falls from 137 mm to 56 mm.
The annual picture
September 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
Asan climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 2.6°C-4.8°C | -4.8°C | 21 | 4.1 | 9.910 h |
| February | 5.2°C-3.5°C | -3.5°C | 28 | 4.2 | 10.811 h |
| March | 10.7°C0.3°C | 0.3°C | 43 | 6.1 | 11.912 h |
| April | 17.4°C6.1°C | 6.1°C | 71 | 6.9 | 13.113 h |
| May | 23.0°C12.0°C | 12.0°C | 80 | 7.3 | 14.114 h |
| June | 27.2°C17.6°C | 17.6°C | 121 | 8.3 | 14.615 h |
| July | 28.7°C21.8°C | 21.8°C | 250 | 16.0 | 14.414 h |
| August | 29.1°C22.4°C | 22.4°C | 234 | 15.0 | 13.614 h |
| September, selected | 25.0°C17.1°C | 17.1°C | 137 | 8.1 | 12.512 h |
| October | 19.1°C10.2°C | 10.2°C | 56 | 5.1 | 11.311 h |
| November | 11.7°C3.2°C | 3.2°C | 45 | 6.2 | 10.210 h |
| December | 4.6°C-2.8°C | -2.8°C | 23 | 4.9 | 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
September in nearby cities
- Cheonan in SeptemberSouth Korea · 13 kmHigh 25.2°C · Low 17.1°C · 139 mm rain
- Pyeongtaek in SeptemberSouth Korea · 25 kmHigh 24.9°C · Low 17.1°C · 127 mm rain
- Sejong in SeptemberSouth Korea · 33 kmHigh 25.2°C · Low 16.9°C · 143 mm rain
- Hongseong in SeptemberSouth Korea · 36 kmHigh 25.1°C · Low 17.4°C · 145 mm rain
- Gongju in SeptemberSouth Korea · 38 kmHigh 25.5°C · Low 17.5°C · 147 mm rain
- Osan in SeptemberSouth Korea · 41 kmHigh 24.8°C · Low 16.9°C · 124 mm rain
- Cheongju-si in SeptemberSouth Korea · 46 kmHigh 25.2°C · Low 17.0°C · 138 mm rain
- Seosan in SeptemberSouth Korea · 49 kmHigh 24.2°C · Low 18.4°C · 133 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 Asan) is explained once on the Asan year overview and on the Sources, method and limits page.