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Niihama, Japan climate
Cfa Humid subtropical
Niihama has a seasonal mild-temperate climate (Humid subtropical, Köppen Cfa). The hottest month is August with an average daily high near 89°F, while the coldest is January averaging around 35°F at night. Precipitation totals about 59 inches a year and is strongly seasonal — September alone averages 9.1 inches while January barely receives 2.09 inches.
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 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)Niihama climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 49 | 50 | 56 | 66 | 75 | 80 | 87 | 89 | 82 | 73 | 63 | 54 |
| Avg temp (°F) | 42 | 43 | 48 | 57 | 66 | 73 | 80 | 81 | 75 | 65 | 55 | 46 |
| Avg low (°F) | 35 | 35 | 40 | 48 | 57 | 66 | 74 | 75 | 69 | 58 | 48 | 39 |
| Precipitation (in) | 2.1 | 2.7 | 4.3 | 4.1 | 5.0 | 8.2 | 7.3 | 4.9 | 9.1 | 6.0 | 2.8 | 2.3 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°F) | 49 | 50 | 56 | 66 | 75 | 80 |
| Avg temp (°F) | 42 | 43 | 48 | 57 | 66 | 73 |
| Avg low (°F) | 35 | 35 | 40 | 48 | 57 | 66 |
| Precipitation (in) | 2.1 | 2.7 | 4.3 | 4.1 | 5.0 | 8.2 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°F) | 87 | 89 | 82 | 73 | 63 | 54 |
| Avg temp (°F) | 80 | 81 | 75 | 65 | 55 | 46 |
| Avg low (°F) | 74 | 75 | 69 | 58 | 48 | 39 |
| Precipitation (in) | 7.3 | 4.9 | 9.1 | 6.0 | 2.8 | 2.3 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 68 | 69 | 68 | 66 | 72 | 83 | 75 | 66 | 72 | 65 | 65 | 65 |
| Relative humidity (%) | 81 | 79 | 77 | 76 | 78 | 82 | 83 | 81 | 81 | 81 | 80 | 81 |
| Wind speed (mph) | 4.8 | 4.7 | 4.5 | 3.8 | 3.1 | 2.7 | 2.8 | 3.0 | 3.5 | 3.9 | 4.0 | 4.5 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 68 | 69 | 68 | 66 | 72 | 83 |
| Relative humidity (%) | 81 | 79 | 77 | 76 | 78 | 82 |
| Wind speed (mph) | 4.8 | 4.7 | 4.5 | 3.8 | 3.1 | 2.7 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 75 | 66 | 72 | 65 | 65 | 65 |
| Relative humidity (%) | 83 | 81 | 81 | 81 | 80 | 81 |
| Wind speed (mph) | 2.8 | 3.0 | 3.5 | 3.9 | 4.0 | 4.5 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from the Japan Meteorological Agency, measured at Saijo, about 21 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.