Climate averages 1991–2020
Iruma weather
in October.
A mild, very wet month: the 6th warmest and the 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
October is a mild month in Iruma: daytime highs average 19.6°C and nights cool to about 12.6°C. By daytime temperature it is the 6th warmest of the 12 months.
Expect about 242 mm of rain on roughly 16 days, which makes October a very wet month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 11 h 19 min on an average October day.
The nearest other city in this atlas is Sayama (6 km away). In October its highs average 19.9°C, about as warm as Iruma, with 215 mm of rain.
Among the 303 cities listed in Japan, Iruma ranks joint 234th of 303 for the warmest October highs and joint 281st of 303 for the driest October (rainfall, lowest first). The mean October high of those 303 cities is 20.4°C; Iruma is 0.8°C cooler than that mean.
From October to November, average highs fall by 5.0°C to 14.6°C, and monthly rainfall falls from 242 mm to 101 mm.
The annual picture
October 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
Iruma climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 7.2°C-2.7°C | -2.7°C | 77 | 8.5 | 10.010 h |
| February | 8.1°C-2.0°C | -2.0°C | 76 | 9.7 | 10.911 h |
| March | 11.7°C1.5°C | 1.5°C | 139 | 15.2 | 11.912 h |
| April | 16.8°C6.8°C | 6.8°C | 146 | 14.6 | 13.113 h |
| May | 21.2°C12.3°C | 12.3°C | 166 | 15.6 | 14.014 h |
| June | 23.8°C16.7°C | 16.7°C | 222 | 19.5 | 14.515 h |
| July | 27.5°C20.9°C | 20.9°C | 243 | 21.8 | 14.314 h |
| August | 28.7°C22.2°C | 22.2°C | 205 | 21.0 | 13.514 h |
| September | 25.0°C18.6°C | 18.6°C | 249 | 18.2 | 12.412 h |
| October, selected | 19.6°C12.6°C | 12.6°C | 242 | 16.2 | 11.311 h |
| November | 14.6°C6.3°C | 6.3°C | 101 | 11.3 | 10.310 h |
| December | 9.7°C0.4°C | 0.4°C | 68 | 8.3 | 9.810 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
October in nearby cities
- Sayama in OctoberJapan · 6 kmHigh 19.9°C · Low 12.7°C · 215 mm rain
- Hannō in OctoberJapan · 6 kmHigh 20.1°C · Low 13.2°C · 242 mm rain
- Tokorozawa in OctoberJapan · 9 kmHigh 19.8°C · Low 12.8°C · 215 mm rain
- Ōme in OctoberJapan · 12 kmHigh 20.0°C · Low 13.1°C · 242 mm rain
- Kawagoe in OctoberJapan · 15 kmHigh 20.1°C · Low 12.9°C · 196 mm rain
- Sakado in OctoberJapan · 16 kmHigh 20.2°C · Low 13.1°C · 196 mm rain
- Akiruno in OctoberJapan · 16 kmHigh 20.0°C · Low 13.2°C · 242 mm rain
- Hino in OctoberJapan · 16 kmHigh 19.9°C · Low 13.0°C · 215 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 Iruma) is explained once on the Iruma year overview and on the Sources, method and limits page.
Hachiōji, Ōme and Akiruno lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.