Isa, Japan Climate
The warmest month is August, with an average high of 30°C; the coldest is January, with an average low of 2°C. A normal year brings 2386 mm of precipitation.
Temperature through the year
The normal daily high and low. The line marks today.
- Normal low
- Normal high
- Reanalysis extreme high
- Reanalysis extreme low
Normals for Sep 25
- Normal high
- 26°C
- Normal low
- 18°C
- Reanalysis high
- 29°Cin 2016
- Reanalysis low
- 12°Cin 1994
- Chance of a wet day
- 47%
- Daylight
- 12 h 04 min
Month by month
Averages for 1991-2020. Wet days have at least 1 mm of precipitation in the reanalysis. Each month links to its own page.
| Month | Avg high | Avg low | Warmest | Coldest | Precipitation | Wet days |
|---|---|---|---|---|---|---|
| January | 10°C | 2°C | 19°C (1998) | -5°C (2016) | 74 mm | 9.3 |
| February | 11°C | 2°C | 21°C (2010) | -6°C (2012) | 102 mm | 8.5 |
| March | 15°C | 5°C | 23°C (2007) | -3°C (2011) | 155 mm | 12.4 |
| April | 19°C | 9°C | 27°C (1998) | -1°C (1993) | 183 mm | 12.0 |
| May | 23°C | 14°C | 30°C (2014) | 6°C (1991) | 208 mm | 12.4 |
| June | 26°C | 19°C | 31°C (1992) | 12°C (2009) | 498 mm | 18.0 |
| July | 29°C | 22°C | 36°C (2010) | 16°C (1992) | 369 mm | 18.6 |
| August | 30°C | 23°C | 36°C (2020) | 15°C (2002) | 229 mm | 18.6 |
| September | 27°C | 20°C | 33°C (2003) | 11°C (1995) | 252 mm | 15.0 |
| October | 23°C | 14°C | 30°C (2017) | 2°C (1997) | 127 mm | 9.3 |
| November | 17°C | 9°C | 26°C (2003) | -1°C (1992) | 105 mm | 9.0 |
| December | 12°C | 4°C | 22°C (2018) | -5°C (2005) | 84 mm | 9.3 |
| Year | 20°C | 12°C | 2386 mm | 152 |
Precipitation
Rain and melted snow together. The chance of a wet day is the share of days with at least 1 mm of precipitation in the reanalysis.
2386 mm in a normal year, most in June.
Chance of a wet day
- Chance of a wet day
Humidity and comfort
NASA POWER reanalysis, 1991-2020, for the grid cell around Isa.
The muggiest month is July, when 100 percent of days are muggy or worse, with a mean dew point of 18°C or more.
| Month | Dew point | Humidity | Dry | Comfortable | Humid | Muggy | Oppressive | Miserable |
|---|---|---|---|---|---|---|---|---|
| January | 2°C | 83% | 99% | 1% | 0% | 0% | 0% | 0% |
| February | 3°C | 81% | 97% | 2% | 0% | 0% | 0% | 0% |
| March | 6°C | 80% | 92% | 7% | 1% | 0% | 0% | 0% |
| April | 10°C | 79% | 71% | 19% | 9% | 2% | 0% | 0% |
| May | 15°C | 81% | 30% | 34% | 24% | 12% | 1% | 0% |
| June | 19°C | 86% | 1% | 9% | 31% | 31% | 28% | 0% |
| July | 23°C | 86% | 0% | 0% | 0% | 12% | 74% | 14% |
| August | 23°C | 85% | 0% | 0% | 1% | 8% | 73% | 18% |
| September | 20°C | 84% | 1% | 7% | 17% | 30% | 42% | 2% |
| October | 15°C | 82% | 30% | 30% | 22% | 13% | 4% | 0% |
| November | 10°C | 83% | 75% | 16% | 7% | 2% | 0% | 0% |
| December | 4°C | 83% | 97% | 3% | 1% | 0% | 0% | 0% |
Comfort is judged by the day's mean dew point: dry below 13°C, comfortable to 16°C, humid to 18°C, muggy to 21°C, oppressive to 24°C, miserable above.
Clouds
Average share of the sky covered, from satellite (CERES and GEWEX SRB) by way of NASA POWER, 1991-2020.
The clearest month is October, with the sky 55 percent covered on average; the cloudiest is June, at 81 percent.
Wind
The mean wind speed over the whole day, from the MERRA-2 reanalysis by way of NASA POWER. Gusts run well above it.
The windiest month is January, averaging 12.6 km/h at 10 meters (33 feet) above the ground.
Daylight and sunshine
The longest day is Jun 19, with 14 h 16 min of daylight; the shortest is Dec 17, with 10 h 03 min.
- Day length
Solar energy
Average daily sunshine reaching the ground on a flat surface, in kilowatt-hours per square meter, clouds included.
Month pages
The weather in Isa in each month, day by day.
What this means
A normal is the average of the thirty years 1991 to 2020, the period the World Meteorological Organization and NOAA use for comparison. It is an average, not a forecast: most days depart from it, and some by a long way.
Where no station record is within reach, the extremes shown are the highest and lowest the reanalysis produced for the date in 1991-2020, not measured records.
Cloud, humidity, wind and sunshine come from a reanalysis: a weather model run over the past with every observation fed in, averaged over a grid cell about 50 km across. It is consistent everywhere on Earth; it smooths local detail such as a lake shore or a valley.
More for this place
Nearby
Sources
Cloud, humidity, wind and sunshine, and temperature and precipitation: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.