| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 21°F | 36°F | 28°F | 4.1" |
| February | 20°F | 37°F | 28°F | 3.0" |
| March | 30°F | 49°F | 39°F | 5.9" |
| April | 40°F | 63°F | 51°F | 4.9" |
| May | 50°F | 72°F | 60°F | 4.9" |
| June | 58°F | 79°F | 68°F | 7.2" |
| July | 62°F | 82°F | 71°F | 7.6" |
| August | 60°F | 80°F | 69°F | 6.5" |
| September | 54°F | 74°F | 63°F | 5.4" |
| October | 44°F | 63°F | 52°F | 4.7" |
| November | 34°F | 51°F | 42°F | 3.8" |
| December | 27°F | 41°F | 33°F | 4.0" |
| Index | Arnold | Pennsylvania | National |
| Air quality index | 56 | 45 | 42 |
| Pollution index | 7,262,690 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 129 |
| Days with moderate air quality | 220 |
| Days w/ poor A.Q. for sensitive groups | 12 |
| Days with unhealthy air quality | 4 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.090% |
| Carbon Tetrachloride | 0.260% |
| Lead | 0.140% |
| Mercury | 0.030% |
| City | Population | Air Quality Index | National Avg. |
| East Vandergrift, PA | 697 | 38 | 24.0% |
| Leechburg, PA | 2,154 | 38 | 24.0% |
| Apollo, PA | 1,408 | 38 | 24.0% |
| North Apollo, PA | 1,186 | 38 | 24.0% |
| Vandergrift, PA | 4,914 | 38 | 24.0% |
| Arnold, PA | 4,852 | 56 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Manheim, PA | 4,852 | 45 | 10.0% |
| Springhill, LA | 4,851 | 39 | 22.0% |
| Midway, NC | 4,851 | 45 | 10.0% |
| Big Pine Key, FL | 4,853 | 41 | 18.0% |
| Folkston, GA | 4,853 | 36 | 28.0% |
| Arnold, PA | 4,852 | 56 | 12.0% |
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