| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 39°F | 28°F | 0.4" |
| February | 18°F | 40°F | 29°F | 0.3" |
| March | 26°F | 52°F | 38°F | 0.3" |
| April | 33°F | 59°F | 45°F | 1.7" |
| May | 41°F | 68°F | 54°F | 2.9" |
| June | 49°F | 77°F | 63°F | 2.6" |
| July | 55°F | 89°F | 72°F | 1.4" |
| August | 54°F | 86°F | 70°F | 1.5" |
| September | 46°F | 76°F | 60°F | 2.0" |
| October | 37°F | 61°F | 48°F | 1.3" |
| November | 26°F | 48°F | 36°F | 0.5" |
| December | 15°F | 36°F | 26°F | 0.4" |
| Index | Carter | Montana | National |
| Air quality index | 21 | 34 | 42 |
| Pollution index | 250,374 | 834,473 | 2,726,193 |
| Measurement | Total |
| Days measured | 363 |
| Days with good air quality | 350 |
| Days with moderate air quality | 12 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.004% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Highwood, MT | 229 | 21 | 58.0% |
| Fort Benton, MT | 1,410 | 21 | 58.0% |
| Carter, MT | 99 | 21 | 58.0% |
| City | Population | Air Quality Index | National Avg. |
| Cullomburg, AL | 99 | 36 | 28.0% |
| Faunsdale, AL | 99 | 35 | 30.0% |
| Black Springs, AR | 99 | 38 | 24.0% |
| Tumacacori-Carmen, AZ | 99 | 31 | 38.0% |
| Alleghany, CA | 99 | 44 | 12.0% |
| Carter, MT | 99 | 21 | 58.0% |
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