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Walla Walla, Washington climate
BSk Cold semi-arid
Walla Walla has a seasonal cool-temperate climate (Cold semi-arid, Köppen BSk). The hottest month is July with an average daily high near 33°C, while the coldest is December averaging around −3°C at night. Precipitation totals about 328 mm a year and is strongly seasonal — December alone averages 39 mm while July barely receives 7 mm.
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)Walla Walla climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°C) | 7 | 9 | 14 | 18 | 23 | 27 | 33 | 32 | 27 | 19 | 11 | 6 |
| Avg temp (°C) | 2 | 4 | 7 | 10 | 15 | 18 | 23 | 23 | 18 | 11 | 5 | 2 |
| Avg low (°C) | −2 | −2 | 1 | 3 | 7 | 10 | 13 | 13 | 9 | 4 | 0 | −3 |
| Precipitation (mm) | 37 | 31 | 34 | 32 | 35 | 29 | 7 | 8 | 12 | 28 | 35 | 39 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°C) | 7 | 9 | 14 | 18 | 23 | 27 |
| Avg temp (°C) | 2 | 4 | 7 | 10 | 15 | 18 |
| Avg low (°C) | −2 | −2 | 1 | 3 | 7 | 10 |
| Precipitation (mm) | 37 | 31 | 34 | 32 | 35 | 29 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°C) | 33 | 32 | 27 | 19 | 11 | 6 |
| Avg temp (°C) | 23 | 23 | 18 | 11 | 5 | 2 |
| Avg low (°C) | 13 | 13 | 9 | 4 | 0 | −3 |
| Precipitation (mm) | 7 | 8 | 12 | 28 | 35 | 39 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 73 | 69 | 69 | 65 | 60 | 50 | 29 | 29 | 39 | 56 | 70 | 73 |
| Relative humidity (%) | 81 | 76 | 70 | 67 | 63 | 59 | 50 | 47 | 50 | 61 | 72 | 80 |
| Wind speed (m/s) | 3.2 | 2.9 | 2.7 | 2.6 | 2.4 | 2.5 | 2.3 | 2.3 | 2.2 | 2.4 | 2.9 | 3.1 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 73 | 69 | 69 | 65 | 60 | 50 |
| Relative humidity (%) | 81 | 76 | 70 | 67 | 63 | 59 |
| Wind speed (m/s) | 3.2 | 2.9 | 2.7 | 2.6 | 2.4 | 2.5 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 29 | 29 | 39 | 56 | 70 | 73 |
| Relative humidity (%) | 50 | 47 | 50 | 61 | 72 | 80 |
| Wind speed (m/s) | 2.3 | 2.3 | 2.2 | 2.4 | 2.9 | 3.1 |
Methodology & sources
Temperature & precipitation — 1991–2020 normals computed from 30 years of daily observations at Eastern OR Regional AT Pendleton AP, a weather station, about 56 km from the city centre. The underlying daily records come from NOAA's global station network.
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.