| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 17°F | 36°F | 26°F | 1.5" |
| February | 17°F | 38°F | 28°F | 1.1" |
| March | 24°F | 48°F | 36°F | 1.3" |
| April | 30°F | 55°F | 43°F | 3.3" |
| May | 37°F | 64°F | 52°F | 3.6" |
| June | 45°F | 74°F | 60°F | 3.9" |
| July | 52°F | 86°F | 70°F | 2.2" |
| August | 50°F | 84°F | 68°F | 2.5" |
| September | 43°F | 73°F | 59°F | 3.6" |
| October | 35°F | 59°F | 47°F | 2.7" |
| November | 25°F | 45°F | 35°F | 1.8" |
| December | 15°F | 34°F | 24°F | 2.2" |
| Index | Ulm | Montana | National |
| Air quality index | 21 | 34 | 42 |
| Pollution index | 1,148,190 | 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 | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.010% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Black Eagle, MT | 836 | 21 | 58.0% |
| Sun Prairie, MT | 1,617 | 21 | 58.0% |
| Fort Shaw, MT | 138 | 21 | 58.0% |
| Sun River, MT | 41 | 21 | 58.0% |
| Gibson Flats, MT | 205 | 21 | 58.0% |
| Ulm, MT | 750 | 21 | 58.0% |
| City | Population | Air Quality Index | National Avg. |
| Pine Ridge, AL | 750 | 39 | 22.0% |
| Garrison, KY | 750 | 14 | 72.0% |
| Rougemont, NC | 750 | 44 | 12.0% |
| Fairmont, NE | 750 | 19 | 62.0% |
| San Jose, NM | 750 | 44 | 12.0% |
| Ulm, MT | 750 | 21 | 58.0% |
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