| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 28°F | 47°F | 37°F | 2.7" |
| February | 29°F | 50°F | 38°F | 2.3" |
| March | 37°F | 60°F | 47°F | 3.2" |
| April | 47°F | 71°F | 58°F | 3.4" |
| May | 56°F | 78°F | 67°F | 4.6" |
| June | 67°F | 87°F | 77°F | 5.3" |
| July | 72°F | 91°F | 81°F | 4.2" |
| August | 70°F | 90°F | 79°F | 3.2" |
| September | 63°F | 83°F | 72°F | 3.5" |
| October | 52°F | 72°F | 61°F | 5.0" |
| November | 40°F | 61°F | 50°F | 2.5" |
| December | 33°F | 52°F | 42°F | 3.8" |
| Index | Deanwood | Washington | District of Columbia |
| Air quality index | 49 | 49 | 49 |
| Pollution index | 849,185 | 5,554,010 | 5,554,010 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 194 |
| Days with moderate air quality | 166 |
| Days w/ poor A.Q. for sensitive groups | 5 |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.060% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.004% |
| Mercury | 0.010% |
| City, State | Population | Air Quality Index | National Avg. |
| Fort Meade, MD | 9,730 | 46 | 8% |
| Odenton, MD | 39,759 | 46 | 8% |
| Maryland City, MD | 17,647 | 46 | 8% |
| Springdale, MD | 2,878 | 49 | 2% |
| University Park, MD | 2,635 | 49 | 2% |
| Washington, DC | 659,009 | 49 | 2% |
| City, State | Population | Air Quality Index | National Avg. |
| Boston, MA | 658,279 | 47 | 6% |
| Memphis, TN | 655,857 | 44 | 12% |
| Denver, CO | 663,303 | 54 | 8% |
| Seattle, WA | 668,849 | 49 | 2% |
| Nashville, TN | 643,771 | 45 | 10% |
| Washington, DC | 659,009 | 49 | 2% |