| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 36°F | 27°F | 2.1" |
| February | 17°F | 35°F | 26°F | 2.2" |
| March | 25°F | 46°F | 35°F | 2.2" |
| April | 36°F | 60°F | 47°F | 3.1" |
| May | 47°F | 72°F | 59°F | 2.9" |
| June | 56°F | 80°F | 68°F | 3.8" |
| July | 61°F | 84°F | 72°F | 4.5" |
| August | 59°F | 82°F | 70°F | 3.5" |
| September | 53°F | 76°F | 64°F | 3.3" |
| October | 43°F | 64°F | 53°F | 4.4" |
| November | 33°F | 52°F | 42°F | 2.6" |
| December | 25°F | 40°F | 32°F | 3.0" |
| Index | Williamson | New York | National |
| Air quality index | 37 | 43 | 42 |
| Pollution index | 2,401,950 | 6,179,275 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 317 |
| Days with moderate air quality | 48 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.030% |
| Mercury | 0.080% |
| City | Population | Air Quality Index | National Avg. |
| Lyons, NY | 3,313 | 37 | 26.0% |
| Port Gibson, NY | 859 | 37 | 26.0% |
| Pultneyville, NY | 655 | 37 | 26.0% |
| Macedon, NY | 1,794 | 37 | 26.0% |
| Ontario, NY | 2,038 | 37 | 26.0% |
| Williamson, NY | 2,642 | 37 | 26.0% |
| City | Population | Air Quality Index | National Avg. |
| Hallam, PA | 2,642 | 41 | 18.0% |
| Claxton, GA | 2,641 | 39 | 22.0% |
| Panorama Village, TX | 2,641 | 52 | 4.0% |
| Waverly, VA | 2,641 | 44 | 12.0% |
| Eutaw, AL | 2,643 | 35 | 30.0% |
| Williamson, NY | 2,642 | 37 | 26.0% |
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