Climate averages 1991–2020
Isahaya weather
in January.
A cool, moderately wet month: the coolest and the driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
January is a cool month in Isahaya: daytime highs average 9.3°C and nights cool to about 5.5°C. By daytime temperature it is the coolest month of the year.
Expect about 79 mm of rain on roughly 11 days, which makes January a moderately wet month (the driest month of the year). Daylight, from sunrise to sunset, lasts about 10 h 15 min on an average January day.
The nearest other city in this atlas is Ōmura (12 km away). In January its highs average 9.6°C, about as warm as Isahaya, with 63 mm of rain.
Among the 303 cities listed in Japan, Isahaya ranks joint 26th of 303 for the warmest January highs and joint 225th of 303 for the driest January (rainfall, lowest first). The mean January high of those 303 cities is 7.0°C; Isahaya is 2.3°C warmer than that mean.
From January to February, average highs rise by 1.0°C to 10.2°C, and monthly rainfall rises from 79 mm to 100 mm.
The annual picture
January 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, selected | 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 | 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
January in nearby cities
- Ōmura in JanuaryJapan · 12 kmHigh 9.6°C · Low 5.7°C · 63 mm rain
- Nagasaki in JanuaryJapan · 18 kmHigh 9.8°C · Low 6.3°C · 79 mm rain
- Ōmuta in JanuaryJapan · 44 kmHigh 9.2°C · Low 3.6°C · 62 mm rain
- Amakusa in JanuaryJapan · 45 kmHigh 10.3°C · Low 5.4°C · 68 mm rain
- Sasebo in JanuaryJapan · 47 kmHigh 9.3°C · Low 5.1°C · 60 mm rain
- Saga in JanuaryJapan · 50 kmHigh 9.1°C · Low 2.9°C · 61 mm rain
- Kumamoto in JanuaryJapan · 61 kmHigh 9.0°C · Low 3.0°C · 78 mm rain
- Honmachi in JanuaryJapan · 64 kmHigh 9.6°C · Low 3.2°C · 73 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.