| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 5°F | 32°F | 17°F | 0.2" |
| February | 10°F | 34°F | 21°F | 0.6" |
| March | 23°F | 51°F | 35°F | 1.7" |
| April | 29°F | 58°F | 43°F | 1.8" |
| May | 40°F | 67°F | 53°F | 5.9" |
| June | 52°F | 78°F | 64°F | 5.0" |
| July | 57°F | 91°F | 74°F | 3.8" |
| August | 52°F | 85°F | 68°F | 3.4" |
| September | 43°F | 77°F | 59°F | 1.9" |
| October | 32°F | 61°F | 45°F | 0.6" |
| November | 20°F | 46°F | 32°F | 0.9" |
| December | 8°F | 31°F | 19°F | 0.8" |
| Index | Morristown | South Dakota | National |
| Air quality index | 36 | 36 | 42 |
| Pollution index | 2,791,680 | 345,623 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 320 |
| Days with moderate air quality | 45 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.120% |
| Benzene | 0.003% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.030% |
| Mercury | 0.050% |
| City | Population | Air Quality Index | National Avg. |
| Morristown, SD | 50 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Tonopah, AZ | 50 | 74 | 48.0% |
| Fish Camp, CA | 50 | 50 | = 100 |
| Lookout, CA | 50 | 29 | 42.0% |
| Idalia, CO | 50 | 58 | 16.0% |
| Pine Island, FL | 50 | 30 | 40.0% |
| Morristown, SD | 50 | 36 | 28.0% |
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