Climate averages 1991–2020
Isahaya weather
in August.
A hot, very wet month: the warmest and the 8th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a hot month in Isahaya: daytime highs average 29.1°C and nights cool to about 24.8°C. By daytime temperature it is the warmest month of the year.
Expect about 185 mm of rain on roughly 14 days, which makes August a very wet month (the 8th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 22 min on an average August day.
The nearest other city in this atlas is Ōmura (12 km away). In August its highs average 29.9°C, 0.8°C warmer than Isahaya, with 179 mm of rain.
Among the 303 cities listed in Japan, Isahaya ranks joint 189th of 303 for the warmest August highs and joint 268th of 303 for the driest August (rainfall, lowest first). The mean August high of those 303 cities is 29.2°C; Isahaya is 0.1°C cooler than that mean.
From August to September, average highs fall by 2.6°C to 26.5°C, and monthly rainfall rises from 185 mm to 202 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
Isahaya climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 9.3°C5.5°C | 5.5°C | 79 | 10.9 | 10.210 h |
| February | 10.2°C5.6°C | 5.6°C | 100 | 10.2 | 11.011 h |
| March | 13.2°C7.9°C | 7.9°C | 149 | 12.0 | 12.012 h |
| April | 17.4°C11.6°C | 11.6°C | 167 | 11.4 | 13.013 h |
| May | 21.3°C15.8°C | 15.8°C | 197 | 10.8 | 13.814 h |
| June | 24.0°C19.6°C | 19.6°C | 444 | 16.5 | 14.314 h |
| July | 27.5°C23.6°C | 23.6°C | 346 | 16.6 | 14.114 h |
| August, selected | 29.1°C24.8°C | 24.8°C | 185 | 13.7 | 13.413 h |
| September | 26.5°C21.9°C | 21.9°C | 202 | 11.9 | 12.412 h |
| October | 21.9°C17.3°C | 17.3°C | 112 | 7.5 | 11.411 h |
| November | 16.8°C12.4°C | 12.4°C | 106 | 9.1 | 10.511 h |
| December | 11.6°C7.7°C | 7.7°C | 92 | 10.3 | 10.010 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
- Ōmura in AugustJapan · 12 kmHigh 29.9°C · Low 25.5°C · 179 mm rain
- Nagasaki in AugustJapan · 18 kmHigh 29.1°C · Low 25.6°C · 185 mm rain
- Ōmuta in AugustJapan · 44 kmHigh 30.2°C · Low 24.2°C · 159 mm rain
- Amakusa in AugustJapan · 45 kmHigh 30.8°C · Low 25.0°C · 183 mm rain
- Sasebo in AugustJapan · 47 kmHigh 30.1°C · Low 25.2°C · 178 mm rain
- Saga in AugustJapan · 50 kmHigh 30.4°C · Low 23.9°C · 181 mm rain
- Kumamoto in AugustJapan · 61 kmHigh 30.4°C · Low 24.0°C · 135 mm rain
- Honmachi in AugustJapan · 64 kmHigh 30.8°C · Low 24.6°C · 162 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 Isahaya) is explained once on the Isahaya year overview and on the Sources, method and limits page.
Nagasaki lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.