Kosai, Japan Climate
The warmest month is August, with an average high of 28°C; the coldest is February, with an average low of 7°C. A normal year brings 1903 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
- 25°C
- Normal low
- 23°C
- Reanalysis high
- 28°Cin 2007
- Reanalysis low
- 20°Cin 2010
- Chance of a wet day
- 50%
- Daylight
- 12 h 03 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 | 11°C | 7°C | 19°C (1993) | 0°C (1997) | 68 mm | 6.2 |
| February | 11°C | 7°C | 20°C (1993) | 1°C (2006) | 82 mm | 8.5 |
| March | 14°C | 9°C | 20°C (2007) | 2°C (2001) | 136 mm | 9.3 |
| April | 17°C | 13°C | 23°C (1998) | 6°C (1996) | 177 mm | 12.0 |
| May | 21°C | 17°C | 26°C (2014) | 10°C (1991) | 189 mm | 12.4 |
| June | 23°C | 21°C | 29°C (2011) | 16°C (1993) | 237 mm | 15.0 |
| July | 27°C | 25°C | 33°C (2018) | 20°C (1993) | 226 mm | 15.5 |
| August | 28°C | 26°C | 33°C (2013) | 22°C (1993) | 155 mm | 15.5 |
| September | 26°C | 24°C | 31°C (2010) | 17°C (2003) | 246 mm | 15.0 |
| October | 22°C | 20°C | 28°C (2013) | 12°C (1997) | 211 mm | 12.4 |
| November | 18°C | 15°C | 25°C (2000) | 7°C (1992) | 108 mm | 9.0 |
| December | 13°C | 10°C | 23°C (2004) | 3°C (2005) | 68 mm | 6.2 |
| Year | 19°C | 16°C | 1903 mm | 137 |
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.
1903 mm in a normal year, most in September.
Chance of a wet day
- Chance of a wet day
Humidity and comfort
NASA POWER reanalysis, 1991-2020, for the grid cell around Kosai.
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 | 5°C | 75% | 99% | 1% | 0% | 0% | 0% | 0% |
| February | 5°C | 73% | 98% | 2% | 0% | 0% | 0% | 0% |
| March | 7°C | 73% | 94% | 5% | 0% | 0% | 0% | 0% |
| April | 11°C | 75% | 66% | 25% | 8% | 1% | 0% | 0% |
| May | 15°C | 80% | 17% | 30% | 40% | 12% | 1% | 0% |
| June | 20°C | 85% | 0% | 5% | 24% | 47% | 23% | 1% |
| July | 23°C | 88% | 0% | 0% | 1% | 12% | 43% | 45% |
| August | 24°C | 85% | 0% | 0% | 0% | 5% | 28% | 67% |
| September | 21°C | 80% | 0% | 4% | 11% | 31% | 34% | 20% |
| October | 16°C | 75% | 11% | 30% | 31% | 21% | 6% | 0% |
| November | 12°C | 73% | 66% | 22% | 10% | 2% | 0% | 0% |
| December | 7°C | 75% | 96% | 3% | 0% | 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 December, with the sky 54 percent covered on average; the cloudiest is June, at 79 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 31.3 km/h at 10 meters (33 feet) above the ground.
Daylight and sunshine
The longest day is Jun 22, with 14 h 30 min of daylight; the shortest is Dec 20, with 9 h 49 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 Kosai 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.