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Iwamizawa, Japan climate
Dfb Warm-summer humid continental
Iwamizawa has a strongly seasonal cool-temperate climate (Warm-summer humid continental, Köppen Dfb). The hottest month is August with an average daily high near 26°C, while the coldest is January averaging around −9°C at night. Around 1259 mm of precipitation falls each year, peaking in August (161 mm) and easing off in April (53 mm). Snowfall is heavy (675 cm of snow per year on average).
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation split into rain and snow · 1991–2020 normals · hover a month for the exact figuresHours of sunshine per day
Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER)Iwamizawa climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | −2 | −1 | 4 | 11 | 18 | 22 | 25 | 26 | 22 | 16 | 8 | 1 |
| Avg temp (°C) | −5 | −5 | 0 | 6 | 12 | 16 | 20 | 21 | 17 | 11 | 4 | −3 |
| Avg low (°C) | −9 | −9 | −5 | 1 | 7 | 12 | 17 | 18 | 13 | 6 | 0 | −6 |
| Precipitation (mm) | 119 | 85 | 59 | 53 | 84 | 69 | 112 | 161 | 142 | 110 | 119 | 145 |
| Snowfall (cm) | 187 | 137 | 72 | 8 | — | — | — | — | — | 1 | 70 | 200 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | −2 | −1 | 4 | 11 | 18 | 22 |
| Avg temp (°C) | −5 | −5 | 0 | 6 | 12 | 16 |
| Avg low (°C) | −9 | −9 | −5 | 1 | 7 | 12 |
| Precipitation (mm) | 119 | 85 | 59 | 53 | 84 | 69 |
| Snowfall (cm) | 187 | 137 | 72 | 8 | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 25 | 26 | 22 | 16 | 8 | 1 |
| Avg temp (°C) | 20 | 21 | 17 | 11 | 4 | −3 |
| Avg low (°C) | 17 | 18 | 13 | 6 | 0 | −6 |
| Precipitation (mm) | 112 | 161 | 142 | 110 | 119 | 145 |
| Snowfall (cm) | — | — | — | 1 | 70 | 200 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 91 | 86 | 79 | 72 | 71 | 73 | 76 | 73 | 72 | 75 | 86 | 91 |
| Relative humidity (%) | 92 | 90 | 87 | 82 | 82 | 84 | 86 | 86 | 85 | 84 | 87 | 91 |
| Wind speed (km/h) | 10.7 | 11.6 | 11.7 | 11.6 | 10.4 | 8.4 | 7.8 | 7.7 | 8.4 | 9.3 | 10.1 | 10.3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 91 | 86 | 79 | 72 | 71 | 73 |
| Relative humidity (%) | 92 | 90 | 87 | 82 | 82 | 84 |
| Wind speed (km/h) | 10.7 | 11.6 | 11.7 | 11.6 | 10.4 | 8.4 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 76 | 73 | 72 | 75 | 86 | 91 |
| Relative humidity (%) | 86 | 86 | 85 | 84 | 87 | 91 |
| Wind speed (km/h) | 7.8 | 7.7 | 8.4 | 9.3 | 10.1 | 10.3 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from the Japan Meteorological Agency, measured at Iwamizawa, about 2 km from the city centre.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.