Climate averages 1991–2020
Iwakuni weather
in September.
A warm, very wet month: the 3rd 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 Iwakuni: daytime highs average 26.5°C and nights cool to about 20.9°C. By daytime temperature it is the 3rd warmest of the 12 months.
Expect about 185 mm of rain on roughly 12 days, which makes September a very wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 25 min on an average September day.
The nearest other city in this atlas is Hatsukaichi (23 km away). In September its highs average 27.3°C, 0.7°C warmer than Iwakuni, with 185 mm of rain.
Among the 303 cities listed in Japan, Iwakuni ranks joint 101st of 303 for the warmest September highs and joint 135th of 303 for the driest September (rainfall, lowest first). The mean September high of those 303 cities is 25.7°C; Iwakuni is 0.9°C warmer than that mean.
From September to October, average highs fall by 5.0°C to 21.5°C, and monthly rainfall falls from 185 mm to 116 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
Iwakuni climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 8.5°C2.8°C | 2.8°C | 50 | 6.2 | 10.210 h |
| February | 9.6°C2.8°C | 2.8°C | 69 | 8.0 | 10.911 h |
| March | 13.0°C5.3°C | 5.3°C | 116 | 10.1 | 11.912 h |
| April | 17.8°C9.9°C | 9.9°C | 138 | 9.7 | 13.013 h |
| May | 22.2°C14.8°C | 14.8°C | 158 | 10.3 | 13.914 h |
| June | 25.1°C19.1°C | 19.1°C | 234 | 13.9 | 14.414 h |
| July | 28.7°C23.4°C | 23.4°C | 255 | 15.2 | 14.214 h |
| August | 29.8°C24.4°C | 24.4°C | 169 | 14.4 | 13.413 h |
| September, selected | 26.5°C20.9°C | 20.9°C | 185 | 11.7 | 12.412 h |
| October | 21.5°C15.5°C | 15.5°C | 116 | 8.0 | 11.411 h |
| November | 16.1°C10.1°C | 10.1°C | 72 | 7.1 | 10.410 h |
| December | 10.8°C5.1°C | 5.1°C | 60 | 6.7 | 9.910 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
- Hatsukaichi in SeptemberJapan · 23 kmHigh 27.3°C · Low 20.5°C · 185 mm rain
- Kure in SeptemberJapan · 33 kmHigh 25.5°C · Low 21.1°C · 163 mm rain
- Hiroshima in SeptemberJapan · 34 kmHigh 26.9°C · Low 19.9°C · 188 mm rain
- Shūnan in SeptemberJapan · 37 kmHigh 25.1°C · Low 19.0°C · 169 mm rain
- Higashihiroshima in SeptemberJapan · 55 kmHigh 26.2°C · Low 19.3°C · 169 mm rain
- Hōfu in SeptemberJapan · 61 kmHigh 27.1°C · Low 20.7°C · 156 mm rain
- Matsuyama in SeptemberJapan · 62 kmHigh 27.3°C · Low 21.5°C · 187 mm rain
- Yamaguchi in SeptemberJapan · 69 kmHigh 26.7°C · Low 19.6°C · 178 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 Iwakuni) is explained once on the Iwakuni year overview and on the Sources, method and limits page.
Hatsukaichi lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.