| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 34°F | 46°F | 39°F | 4.4" |
| February | 36°F | 52°F | 43°F | 4.5" |
| March | 40°F | 60°F | 49°F | 6.7" |
| April | 42°F | 61°F | 51°F | 4.9" |
| May | 48°F | 70°F | 58°F | 4.0" |
| June | 51°F | 72°F | 61°F | 4.2" |
| July | 57°F | 84°F | 69°F | 1.7" |
| August | 54°F | 84°F | 67°F | 5.0" |
| September | 48°F | 75°F | 60°F | 3.9" |
| October | 47°F | 63°F | 54°F | 5.4" |
| November | 38°F | 51°F | 44°F | 8.4" |
| December | 35°F | 45°F | 39°F | 11.5" |
| Index | Stevenson | Washington | National |
| Air quality index | 23 | 36 | 42 |
| Pollution index | 714,613 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 350 |
| Days with good air quality | 298 |
| Days with moderate air quality | 52 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Cascade Locks, OR | 1,509 | 23 | 54.0% |
| Carson, WA | 2,800 | 23 | 54.0% |
| Parkdale, OR | 308 | 23 | 54.0% |
| North Bonneville, WA | 995 | 38 | 24.0% |
| Stevenson, WA | 1,414 | 23 | 54.0% |
| City | Population | Air Quality Index | National Avg. |
| Tuolumne City, CA | 1,414 | 39 | 22.0% |
| Bridgeport, NE | 1,414 | 19 | 62.0% |
| Niverville, NY | 1,414 | 37 | 26.0% |
| Saint-Tite-des-Caps, QC | 1,414 | n/a | |
| Chualar, CA | 1,413 | 37 | 26.0% |
| Stevenson, WA | 1,414 | 23 | 54.0% |
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