| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 48°F | 32°F | 1.2" |
| February | 21°F | 50°F | 34°F | 1.5" |
| March | 30°F | 62°F | 44°F | 1.6" |
| April | 36°F | 66°F | 49°F | 0.2" |
| May | 43°F | 73°F | 57°F | 2.4" |
| June | 54°F | 89°F | 71°F | 1.1" |
| July | 59°F | 92°F | 75°F | 2.1" |
| August | 56°F | 90°F | 72°F | 1.1" |
| September | 49°F | 82°F | 64°F | 0.2" |
| October | 38°F | 69°F | 52°F | 2.1" |
| November | 28°F | 58°F | 41°F | 2.6" |
| December | 17°F | 46°F | 30°F | 0.7" |
| Index | St. Mary's | Colorado | National |
| Air quality index | 47 | 38 | 50 |
| Pollution index | 10,378,100 | 2,034,619 | 5,066,862 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 227 |
| Days with moderate air quality | 133 |
| Days w/ poor A.Q. for sensitive groups | 5 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.770% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 2.620% |
| Lead | 0.070% |
| Mercury | 0.240% |
| City, State | Population | Air Quality Index | National Avg. |
| St. Ann Highlands, CO | 366 | 47 | 6% |
| Black Hawk, CO | 166 | 47 | 6% |
| Floyd Hill, CO | 1,063 | 47 | 6% |
| Eldora, CO | 119 | 47 | 6% |
| Mountain Meadows, CO | 167 | 47 | 6% |
| St. Mary's, CO | 329 | 47 | 6% |
| City, State | Population | Air Quality Index | National Avg. |
| Flat Rock, IL | 329 | 36 | 28% |
| Westside, IA | 329 | 35 | 30% |
| Bradfordsville, KY | 329 | 40 | 20% |
| Lakeview Heights, KY | 329 | 14 | 72% |
| Custer City, OK | 329 | 43 | 14% |
| St. Mary's, CO | 329 | 47 | 6% |
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