| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 19°F | 46°F | 32°F | 0.5" |
| February | 20°F | 48°F | 33°F | 0.5" |
| March | 28°F | 58°F | 42°F | 0.9" |
| April | 33°F | 63°F | 47°F | 2.0" |
| May | 42°F | 70°F | 55°F | 2.3" |
| June | 53°F | 85°F | 68°F | 2.0" |
| July | 59°F | 88°F | 73°F | 2.3" |
| August | 57°F | 86°F | 71°F | 2.1" |
| September | 49°F | 79°F | 63°F | 1.7" |
| October | 37°F | 67°F | 51°F | 1.3" |
| November | 28°F | 58°F | 41°F | 0.4" |
| December | 18°F | 45°F | 30°F | 0.5" |
| Index | Littleton | Colorado | National |
| Air quality index | 58 | 38 | 42 |
| Pollution index | 331,475 | 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 | 0.000% |
| Benzene | 0.004% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.001% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Mountain View, CO | 565 | 58 | 16.0% |
| Castle Pines Village, CO | 4,558 | 58 | 16.0% |
| Roxborough Park, CO | 9,004 | 58 | 16.0% |
| Genesee, CO | 4,099 | 58 | 16.0% |
| Acres Green, CO | 2,888 | 58 | 16.0% |
| Littleton, CO | 46,208 | 58 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Horizon West, FL | 46,204 | 39 | 22.0% |
| West Vancouver, BC | 46,220 | n/a | |
| Mission, BC | 46,224 | n/a | |
| Potomac, MD | 46,256 | 47 | 6.0% |
| Everett, MA | 46,275 | 43 | 14.0% |
| Littleton, CO | 46,208 | 58 | 16.0% |
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