| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 34°F | 48°F | 40°F | 4.1" |
| February | 35°F | 53°F | 43°F | 3.9" |
| March | 40°F | 61°F | 49°F | 4.7" |
| April | 42°F | 62°F | 51°F | 3.1" |
| May | 48°F | 70°F | 58°F | 4.2" |
| June | 51°F | 73°F | 60°F | 2.3" |
| July | 56°F | 84°F | 69°F | 2.0" |
| August | 55°F | 85°F | 68°F | 4.3" |
| September | 49°F | 76°F | 61°F | 4.5" |
| October | 46°F | 62°F | 53°F | 5.6" |
| November | 36°F | 53°F | 43°F | 5.8" |
| December | 35°F | 47°F | 40°F | 10.1" |
| Index | Gladstone | Oregon | National |
| Air quality index | 38 | 32 | 42 |
| Pollution index | 11,541,100 | 7,156,356 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 285 |
| Days with moderate air quality | 77 |
| Days w/ poor A.Q. for sensitive groups | 3 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.140% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.020% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Hubbard, OR | 3,527 | 32 | 36.0% |
| Donald, OR | 1,465 | 32 | 36.0% |
| Fairview, OR | 9,382 | 38 | 24.0% |
| Wood Village, OR | 4,069 | 38 | 24.0% |
| Durham, OR | 1,764 | 38 | 24.0% |
| Gladstone, OR | 12,316 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Effingham, IL | 12,310 | 40 | 20.0% |
| Ottawa, KS | 12,308 | 41 | 18.0% |
| Saddlebrooke, AZ | 12,327 | 47 | 6.0% |
| Speedway, IN | 12,327 | 54 | 8.0% |
| Tamalpais-Homestead Valley, CA | 12,331 | 40 | 20.0% |
| Gladstone, OR | 12,316 | 38 | 24.0% |
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