| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 43°F | 29°F | 2.2" |
| February | 24°F | 51°F | 36°F | 1.7" |
| March | 30°F | 62°F | 45°F | 1.4" |
| April | 35°F | 69°F | 52°F | 1.6" |
| May | 43°F | 78°F | 61°F | 1.4" |
| June | 52°F | 91°F | 73°F | 0.9" |
| July | 61°F | 94°F | 77°F | 0.9" |
| August | 59°F | 90°F | 74°F | 1.9" |
| September | 51°F | 83°F | 66°F | 2.9" |
| October | 38°F | 71°F | 53°F | 2.5" |
| November | 28°F | 58°F | 41°F | 2.0" |
| December | 20°F | 45°F | 31°F | 1.8" |
| Index | Williams | Arizona | National |
| Air quality index | 45 | 57 | 42 |
| Pollution index | 15,258,300 | 9,766,019 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 293 |
| Days with moderate air quality | 72 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.430% |
| Benzene | 0.060% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.130% |
| Mercury | 0.150% |
| City | Population | Air Quality Index | National Avg. |
| Parks, AZ | 1,388 | 45 | 10.0% |
| Williams, AZ | 3,234 | 45 | 10.0% |
| City | Population | Air Quality Index | National Avg. |
| Moscow Mills, MO | 3,234 | 54 | 8.0% |
| Cascade Valley, WA | 3,234 | 18 | 64.0% |
| Holton, KS | 3,233 | 41 | 18.0% |
| Port Hawkesbury, NS | 3,233 | n/a | |
| Opportunity No. 17, AB | 3,232 | n/a | |
| Williams, AZ | 3,234 | 45 | 10.0% |
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