Climate averages 1991–2020
Niihama weather
in August.
A hot, wet month: the warmest and the 7th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a hot month in Niihama: daytime highs average 30.6°C and nights cool to about 24.8°C. By daytime temperature it is the warmest month of the year.
Expect about 151 mm of rain on roughly 14 days, which makes August a wet month (the 7th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 25 min on an average August day.
The nearest other city in this atlas is Saijō (12 km away). In August its highs average 31.3°C, 0.7°C warmer than Niihama, with 151 mm of rain.
Among the 303 cities listed in Japan, Niihama ranks joint 49th of 303 for the warmest August highs and joint 161st of 303 for the driest August (rainfall, lowest first). The mean August high of those 303 cities is 29.2°C; Niihama is 1.4°C warmer than that mean.
From August to September, average highs fall by 3.5°C to 27.1°C, and monthly rainfall rises from 151 mm to 216 mm.
The annual picture
August 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
Niihama climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 9.0°C3.3°C | 3.3°C | 78 | 13.5 | 10.210 h |
| February | 10.1°C3.3°C | 3.3°C | 86 | 12.3 | 10.911 h |
| March | 13.6°C5.8°C | 5.8°C | 122 | 13.4 | 12.012 h |
| April | 18.5°C10.4°C | 10.4°C | 134 | 11.6 | 13.013 h |
| May | 22.8°C15.1°C | 15.1°C | 158 | 11.2 | 13.914 h |
| June | 25.8°C19.5°C | 19.5°C | 249 | 15.1 | 14.414 h |
| July | 29.5°C23.9°C | 23.9°C | 228 | 15.6 | 14.214 h |
| August, selected | 30.6°C24.8°C | 24.8°C | 151 | 13.8 | 13.413 h |
| September | 27.1°C21.4°C | 21.4°C | 216 | 14.1 | 12.412 h |
| October | 21.9°C15.7°C | 15.7°C | 166 | 11.0 | 11.411 h |
| November | 16.6°C10.2°C | 10.2°C | 90 | 9.9 | 10.410 h |
| December | 11.4°C5.5°C | 5.5°C | 90 | 12.8 | 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
August in nearby cities
- Saijō in AugustJapan · 12 kmHigh 31.3°C · Low 25.2°C · 151 mm rain
- Shikokuchūō in AugustJapan · 23 kmHigh 30.7°C · Low 24.6°C · 182 mm rain
- Imabari in AugustJapan · 31 kmHigh 29.7°C · Low 25.0°C · 142 mm rain
- Shinagawa in AugustJapan · 45 kmHigh 29.7°C · Low 23.3°C · 194 mm rain
- Kochi in AugustJapan · 50 kmHigh 29.6°C · Low 23.6°C · 297 mm rain
- Matsuyama in AugustJapan · 52 kmHigh 30.7°C · Low 24.9°C · 156 mm rain
- Onomichi in AugustJapan · 52 kmHigh 30.5°C · Low 24.0°C · 107 mm rain
- Mihara in AugustJapan · 53 kmHigh 30.9°C · Low 24.3°C · 125 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 Niihama) is explained once on the Niihama year overview and on the Sources, method and limits page.
Saijō lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.