Climate averages 1991–2020
Isahaya weather
in May.
A mild, very wet month: the 6th warmest and the 9th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
May is a mild month in Isahaya: daytime highs average 21.3°C and nights cool to about 15.8°C. By daytime temperature it is the 6th warmest of the 12 months.
Expect about 197 mm of rain on roughly 11 days, which makes May a very wet month (the 9th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 50 min on an average May day.
The nearest other city in this atlas is Ōmura (12 km away). In May its highs average 22.2°C, 1.0°C warmer than Isahaya, with 173 mm of rain.
Among the 303 cities listed in Japan, Isahaya ranks joint 185th of 303 for the warmest May highs and joint 282nd of 303 for the driest May (rainfall, lowest first). The mean May high of those 303 cities is 21.3°C; Isahaya is 0.1°C cooler than that mean.
From May to June, average highs rise by 2.7°C to 24.0°C, and monthly rainfall rises from 197 mm to 444 mm.
The annual picture
May 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, selected | 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
May in nearby cities
- Ōmura in MayJapan · 12 kmHigh 22.2°C · Low 16.4°C · 173 mm rain
- Nagasaki in MayJapan · 18 kmHigh 21.2°C · Low 16.7°C · 197 mm rain
- Ōmuta in MayJapan · 44 kmHigh 23.0°C · Low 15.0°C · 172 mm rain
- Amakusa in MayJapan · 45 kmHigh 23.3°C · Low 16.1°C · 181 mm rain
- Sasebo in MayJapan · 47 kmHigh 22.4°C · Low 15.9°C · 149 mm rain
- Saga in MayJapan · 50 kmHigh 23.2°C · Low 14.4°C · 164 mm rain
- Kumamoto in MayJapan · 61 kmHigh 23.2°C · Low 15.2°C · 178 mm rain
- Honmachi in MayJapan · 64 kmHigh 23.8°C · Low 16.1°C · 174 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.