| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 3°F | 25°F | 13°F | 2.4" |
| February | 5°F | 27°F | 15°F | 1.2" |
| March | 17°F | 41°F | 27°F | 1.2" |
| April | 27°F | 57°F | 41°F | 1.2" |
| May | 37°F | 67°F | 52°F | 2.3" |
| June | 47°F | 75°F | 61°F | 4.6" |
| July | 52°F | 85°F | 67°F | 4.2" |
| August | 49°F | 83°F | 65°F | 2.3" |
| September | 41°F | 73°F | 55°F | 1.8" |
| October | 29°F | 58°F | 41°F | 1.3" |
| November | 17°F | 41°F | 27°F | 1.4" |
| December | 2°F | 23°F | 12°F | 2.6" |
| Index | Plentywood | Montana | National |
| Air quality index | 34 | 34 | 42 |
| Pollution index | 563,599 | 834,473 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 309 |
| Days with moderate air quality | 53 |
| 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 | 0.001% |
| Lead | 0.010% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Reserve, MT | 36 | 34 | 32.0% |
| Antelope, MT | 47 | 34 | 32.0% |
| Outlook, MT | 102 | 34 | 32.0% |
| Plentywood, MT | 1,527 | 34 | 32.0% |
| City | Population | Air Quality Index | National Avg. |
| Mammoth, AZ | 1,527 | 47 | 6.0% |
| New Market, MD | 1,527 | 40 | 20.0% |
| Limestone, ME | 1,527 | 31 | 38.0% |
| Edgeworth, PA | 1,527 | 56 | 12.0% |
| Ferndale, PA | 1,527 | 39 | 22.0% |
| Plentywood, MT | 1,527 | 34 | 32.0% |
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