| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 29°F | 48°F | 37°F | 2.3" |
| February | 23°F | 44°F | 32°F | 2.7" |
| March | 33°F | 56°F | 43°F | 7.5" |
| April | 42°F | 68°F | 54°F | 6.5" |
| May | 50°F | 76°F | 63°F | 15.9" |
| June | 62°F | 87°F | 73°F | 3.1" |
| July | 67°F | 89°F | 76°F | 13.9" |
| August | 67°F | 90°F | 77°F | 4.3" |
| September | 57°F | 85°F | 70°F | 0.7" |
| October | 50°F | 74°F | 60°F | 3.0" |
| November | 36°F | 61°F | 47°F | 4.5" |
| December | 27°F | 47°F | 36°F | 4.2" |
| Index | Clifton | Virginia | National |
| Air quality index | 47 | 58 | 42 |
| Pollution index | 205,216 | 1,561,881 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 209 |
| Days with moderate air quality | 145 |
| Days w/ poor A.Q. for sensitive groups | 10 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.002% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Manassas, VA | 41,038 | 47 | 6.0% |
| Dulles Town Center, VA | 5,362 | 47 | 6.0% |
| Catlett, VA | 54 | 47 | 6.0% |
| Centreville, VA | 74,230 | 47 | 6.0% |
| Sudley, VA | 18,019 | 47 | 6.0% |
| Clifton, VA | 309 | 47 | 6.0% |
| City | Population | Air Quality Index | National Avg. |
| Dillon Beach, CA | 309 | 34 | 32.0% |
| Esto, FL | 309 | 35 | 30.0% |
| Martelle, IA | 309 | 39 | 22.0% |
| Bancroft, ID | 309 | 27 | 46.0% |
| Hollister, ID | 309 | 20 | 60.0% |
| Clifton, VA | 309 | 47 | 6.0% |
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