| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 26°F | 35°F | 30°F | 13.2" |
| February | 28°F | 37°F | 32°F | 5.0" |
| March | 31°F | 41°F | 35°F | 7.4" |
| April | 35°F | 49°F | 41°F | 10.0" |
| May | 42°F | 58°F | 49°F | 3.1" |
| June | 47°F | 61°F | 54°F | 4.1" |
| July | 51°F | 62°F | 55°F | 9.0" |
| August | 49°F | 64°F | 56°F | 17.4" |
| September | 46°F | 55°F | 50°F | 7.5" |
| October | 38°F | 48°F | 43°F | 5.1" |
| November | 33°F | 42°F | 37°F | 23.1" |
| December | 28°F | 37°F | 32°F | 10.8" |
| Index | Petersburg | Alaska | National |
| Air quality index | 20 | 30 | 50 |
| Pollution index | 285,879 | 11,990,286 | 5,066,862 |
| Measurement | Total |
| Days measured | 362 |
| Days with good air quality | 308 |
| Days with moderate air quality | 51 |
| Days w/ poor A.Q. for sensitive groups | 3 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City, State | Population | Air Quality Index | National Avg. |
| Kupreanof, AK | 24 | 20 | 60% |
| Petersburg, AK | 2,996 | 20 | 60% |
| City, State | Population | Air Quality Index | National Avg. |
| Silt, CO | 2,996 | 44 | 12% |
| Marion, KY | 2,997 | 44 | 12% |
| Iuka, MS | 2,997 | 37 | 26% |
| Stamford, TX | 2,995 | 26 | 48% |
| Upton, MA | 2,998 | 40 | 20% |
| Petersburg, AK | 2,996 | 20 | 60% |
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