| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 17°F | 32°F | 24°F | 2.1" |
| February | 16°F | 32°F | 24°F | 1.9" |
| March | 25°F | 43°F | 33°F | 2.5" |
| April | 36°F | 58°F | 46°F | 3.1" |
| May | 46°F | 69°F | 57°F | 3.5" |
| June | 54°F | 75°F | 64°F | 4.2" |
| July | 58°F | 79°F | 68°F | 4.3" |
| August | 56°F | 77°F | 66°F | 3.9" |
| September | 51°F | 71°F | 60°F | 3.5" |
| October | 42°F | 60°F | 50°F | 4.3" |
| November | 32°F | 48°F | 39°F | 2.2" |
| December | 24°F | 37°F | 30°F | 3.1" |
| Index | Portville | New York | National |
| Air quality index | 35 | 43 | 42 |
| Pollution index | 2,885,140 | 6,179,275 | 2,726,193 |
| Measurement | Total |
| Days measured | 357 |
| Days with good air quality | 345 |
| Days with moderate air quality | 12 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.004% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.005% |
| Lead | 0.010% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Allegany, NY | 1,981 | 9 | 82.0% |
| St. Bonaventure, NY | 2,015 | 9 | 82.0% |
| Foster Brook, PA | 1,115 | 9 | 82.0% |
| Weston Mills, NY | 1,297 | 9 | 82.0% |
| Olean, NY | 13,580 | 9 | 82.0% |
| Portville, NY | 943 | 35 | 30.0% |
| City | Population | Air Quality Index | National Avg. |
| Town Creek, AL | 943 | 37 | 26.0% |
| Cascade-Chipita Park, CO | 943 | 45 | 10.0% |
| Waldo, FL | 943 | 35 | 30.0% |
| Dexter, GA | 943 | 38 | 24.0% |
| Elk Run Heights, IA | 943 | 39 | 22.0% |
| Portville, NY | 943 | 35 | 30.0% |
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