| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 30°F | 43°F | 36°F | 2.2" |
| February | 32°F | 51°F | 40°F | 1.4" |
| March | 36°F | 59°F | 46°F | 1.5" |
| April | 41°F | 66°F | 52°F | 0.8" |
| May | 48°F | 76°F | 61°F | 1.0" |
| June | 55°F | 82°F | 67°F | 0.5" |
| July | 60°F | 92°F | 75°F | 0.1" |
| August | 59°F | 91°F | 75°F | 0.2" |
| September | 52°F | 83°F | 66°F | 0.4" |
| October | 43°F | 67°F | 54°F | 1.3" |
| November | 35°F | 53°F | 43°F | 2.1" |
| December | 29°F | 42°F | 35°F | 3.1" |
| Index | The Dalles | Oregon | National |
| Air quality index | 23 | 32 | 42 |
| Pollution index | 1,957,960 | 7,156,356 | 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 | 0.001% |
| Benzene | 0.040% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.010% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Rowena, OR | 203 | 23 | 54.0% |
| Wishram, WA | 537 | 23 | 54.0% |
| Chenoweth, OR | 1,703 | 23 | 54.0% |
| Lyle, WA | 267 | 23 | 54.0% |
| Dufur, OR | 822 | 23 | 54.0% |
| The Dalles, OR | 15,518 | 23 | 54.0% |
| City | Population | Air Quality Index | National Avg. |
| Longwood, FL | 15,514 | 37 | 26.0% |
| Middleburg Heights, OH | 15,514 | 50 | = 100 |
| Traverse City, MI | 15,525 | 36 | 28.0% |
| Coto de Caza, CA | 15,509 | 89 | 78.0% |
| Groves, TX | 15,531 | 45 | 10.0% |
| The Dalles, OR | 15,518 | 23 | 54.0% |
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