| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 19°F | 33°F | 26°F | 2.7" |
| February | 18°F | 34°F | 26°F | 2.5" |
| March | 28°F | 46°F | 36°F | 3.3" |
| April | 39°F | 60°F | 48°F | 3.6" |
| May | 49°F | 70°F | 59°F | 3.8" |
| June | 57°F | 77°F | 66°F | 5.2" |
| July | 61°F | 81°F | 70°F | 4.7" |
| August | 60°F | 79°F | 69°F | 4.2" |
| September | 54°F | 73°F | 63°F | 4.2" |
| October | 44°F | 61°F | 52°F | 4.6" |
| November | 34°F | 50°F | 41°F | 3.1" |
| December | 25°F | 38°F | 31°F | 3.6" |
| Index | Jamestown | Pennsylvania | National |
| Air quality index | 42 | 45 | 42 |
| Pollution index | 3,855,270 | 4,584,805 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 276 |
| Days with moderate air quality | 89 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.003% |
| Benzene | 0.040% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.020% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Fredonia, PA | 320 | 31 | 38.0% |
| Lake Latonka, PA | 756 | 31 | 38.0% |
| Sheakleyville, PA | 140 | 31 | 38.0% |
| Conneaut Lakeshore, PA | 2,036 | 34 | 32.0% |
| Harmonsburg, PA | 366 | 34 | 32.0% |
| Jamestown, PA | 761 | 42 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Manokotak, AK | 761 | 31 | 38.0% |
| Independence, CA | 761 | 47 | 6.0% |
| Duck Key, FL | 761 | 41 | 18.0% |
| Ventura, IA | 761 | 15 | 70.0% |
| Challis, ID | 761 | 36 | 28.0% |
| Jamestown, PA | 761 | 42 | 16.0% |
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