| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 14°F | 34°F | 23°F | 0.1" |
| February | 18°F | 40°F | 27°F | 0.3" |
| March | 23°F | 47°F | 33°F | 0.7" |
| April | 29°F | 55°F | 40°F | 1.6" |
| May | 37°F | 65°F | 50°F | 1.9" |
| June | 43°F | 72°F | 57°F | 2.2" |
| July | 50°F | 85°F | 67°F | 1.3" |
| August | 47°F | 83°F | 64°F | 0.9" |
| September | 40°F | 73°F | 55°F | 1.2" |
| October | 32°F | 57°F | 42°F | 1.3" |
| November | 23°F | 45°F | 33°F | 0.5" |
| December | 11°F | 31°F | 20°F | 0.2" |
| Index | Sheridan | Montana | National |
| Air quality index | 20 | 34 | 42 |
| Pollution index | 293,782 | 834,473 | 2,726,193 |
| Measurement | Total |
| Days measured | 363 |
| Days with good air quality | 319 |
| Days with moderate air quality | 44 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| 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. |
| Alder, MT | 96 | 20 | 60.0% |
| Twin Bridges, MT | 232 | 20 | 60.0% |
| Virginia City, MT | 175 | 25 | 50.0% |
| Sheridan, MT | 897 | 20 | 60.0% |
| City | Population | Air Quality Index | National Avg. |
| Toksook Bay, AK | 897 | 31 | 38.0% |
| Many Farms, AZ | 897 | 17 | 66.0% |
| Occidental, CA | 897 | 34 | 32.0% |
| Branford, FL | 897 | 38 | 24.0% |
| Matherville, IL | 897 | 46 | 8.0% |
| Sheridan, MT | 897 | 20 | 60.0% |