| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 46°F | 40°F | 4.7" |
| February | 38°F | 51°F | 44°F | 3.2" |
| March | 40°F | 57°F | 47°F | 5.2" |
| April | 42°F | 63°F | 51°F | 3.6" |
| May | 48°F | 71°F | 58°F | 2.8" |
| June | 53°F | 76°F | 63°F | 2.1" |
| July | 56°F | 84°F | 69°F | 0.5" |
| August | 56°F | 85°F | 69°F | 0.4" |
| September | 52°F | 78°F | 64°F | 1.6" |
| October | 46°F | 65°F | 55°F | 4.5" |
| November | 42°F | 53°F | 47°F | 6.5" |
| December | 35°F | 45°F | 40°F | 5.1" |
| Index | Happy Valley | Oregon | National |
| Air quality index | 38 | 32 | 42 |
| Pollution index | 24,235,400 | 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 | 0.020% |
| Benzene | 0.250% |
| Carbon Tetrachloride | 0.060% |
| Lead | 0.160% |
| Mercury | 0.090% |
| City | Population | Air Quality Index | National Avg. |
| Gresham, OR | 110,456 | 38 | 24.0% |
| Camas, WA | 24,043 | 38 | 24.0% |
| Durham, OR | 1,764 | 38 | 24.0% |
| King City, OR | 4,345 | 38 | 24.0% |
| Oak Grove, OR | 17,781 | 38 | 24.0% |
| Happy Valley, OR | 22,049 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Vicksburg, MS | 22,045 | 44 | 12.0% |
| Fairhope, AL | 22,035 | 37 | 26.0% |
| King of Prussia, PA | 22,028 | 51 | 2.0% |
| Essex, ON | 22,025 | n/a | |
| Huntsville, ON | 22,073 | n/a | |
| Happy Valley, OR | 22,049 | 38 | 24.0% |
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