| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 21°F | 45°F | 31°F | 1.8" |
| February | 22°F | 46°F | 32°F | 2.0" |
| March | 30°F | 58°F | 42°F | 2.1" |
| April | 35°F | 63°F | 47°F | 4.0" |
| May | 44°F | 70°F | 55°F | 5.2" |
| June | 54°F | 84°F | 68°F | 4.6" |
| July | 60°F | 89°F | 73°F | 5.7" |
| August | 59°F | 87°F | 71°F | 4.5" |
| September | 51°F | 79°F | 63°F | 5.7" |
| October | 39°F | 67°F | 51°F | 4.1" |
| November | 29°F | 56°F | 41°F | 2.2" |
| December | 19°F | 44°F | 30°F | 2.9" |
| Index | Derby | Colorado | National |
| Air quality index | 58 | 38 | 42 |
| Pollution index | 872,309 | 2,068,342 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 91 |
| Days with moderate air quality | 252 |
| Days w/ poor A.Q. for sensitive groups | 20 |
| Days with unhealthy air quality | 2 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.010% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Superior, CO | 13,292 | 47 | 6.0% |
| Louisville, CO | 19,342 | 47 | 6.0% |
| Erie, CO | 27,157 | 47 | 6.0% |
| Leyner, CO | 0 | 47 | 6.0% |
| Lafayette, CO | 27,952 | 47 | 6.0% |
| Derby, CO | 9,156 | 58 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Calimesa, CA | 9,156 | 89 | 78.0% |
| Greenville, NY | 9,155 | 51 | 2.0% |
| Anaconda-Deer Lodge County, MT | 9,153 | 20 | 60.0% |
| Incline Village, NV | 9,160 | 41 | 18.0% |
| Gresham Park, GA | 9,148 | 52 | 4.0% |
| Derby, CO | 9,156 | 58 | 16.0% |
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