| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 34°F | 48°F | 40°F | 4.9" |
| February | 36°F | 53°F | 43°F | 3.4" |
| March | 39°F | 58°F | 48°F | 4.8" |
| April | 42°F | 63°F | 52°F | 3.0" |
| May | 48°F | 71°F | 58°F | 2.8" |
| June | 53°F | 76°F | 63°F | 1.7" |
| July | 57°F | 84°F | 69°F | 0.5" |
| August | 58°F | 85°F | 70°F | 0.5" |
| September | 53°F | 78°F | 64°F | 1.8" |
| October | 47°F | 66°F | 55°F | 3.7" |
| November | 40°F | 55°F | 47°F | 6.2" |
| December | 34°F | 47°F | 40°F | 6.2" |
| Index | Hockinson | Washington | National |
| Air quality index | 38 | 36 | 42 |
| Pollution index | 1,899,410 | 4,541,850 | 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 | 0.003% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.010% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Woodland, WA | 6,439 | 18 | 64.0% |
| Fairview, OR | 9,680 | 38 | 24.0% |
| Amboy, WA | 1,939 | 38 | 24.0% |
| Fern Prairie, WA | 2,040 | 38 | 24.0% |
| Venersborg, WA | 4,092 | 38 | 24.0% |
| Hockinson, WA | 6,285 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Independence, IA | 6,286 | 39 | 22.0% |
| Violet, LA | 6,286 | 45 | 10.0% |
| Sheridan, OR | 6,288 | 32 | 36.0% |
| South Williamsport, PA | 6,281 | 35 | 30.0% |
| Munford, TN | 6,289 | 45 | 10.0% |
| Hockinson, WA | 6,285 | 38 | 24.0% |