| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 40°F | 32°F | 2.5" |
| February | 24°F | 43°F | 33°F | 2.3" |
| March | 33°F | 53°F | 42°F | 2.7" |
| April | 43°F | 66°F | 54°F | 3.9" |
| May | 52°F | 75°F | 63°F | 3.9" |
| June | 62°F | 83°F | 73°F | 4.6" |
| July | 67°F | 87°F | 77°F | 4.4" |
| August | 64°F | 85°F | 74°F | 4.2" |
| September | 58°F | 79°F | 68°F | 3.4" |
| October | 47°F | 67°F | 56°F | 5.1" |
| November | 36°F | 55°F | 45°F | 2.4" |
| December | 29°F | 45°F | 36°F | 3.7" |
| Index | Mount Holly Springs | Pennsylvania | National |
| Air quality index | 42 | 45 | 42 |
| Pollution index | 12,532,500 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 288 |
| Days with moderate air quality | 77 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.180% |
| Benzene | 0.090% |
| Carbon Tetrachloride | 0.020% |
| Lead | 0.130% |
| Mercury | 0.270% |
| City | Population | Air Quality Index | National Avg. |
| Newville, PA | 1,231 | 36 | 28.0% |
| East Berlin, PA | 1,570 | 41 | 18.0% |
| Wellsville, PA | 257 | 41 | 18.0% |
| Arendtsville, PA | 855 | 42 | 16.0% |
| Hampton, PA | 1,921 | 42 | 16.0% |
| Mount Holly Springs, PA | 2,037 | 42 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Bertsch-Oceanview, CA | 2,037 | 20 | 60.0% |
| Montz, LA | 2,037 | 45 | 10.0% |
| Essex Fells, NJ | 2,037 | 51 | 2.0% |
| Blackville, SC | 2,037 | 47 | 6.0% |
| Provost No. 52, AB | 2,037 | n/a | |
| Mount Holly Springs, PA | 2,037 | 42 | 16.0% |
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