| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 27°F | 45°F | 35°F | 4.8" |
| February | 28°F | 47°F | 36°F | 6.4" |
| March | 36°F | 57°F | 46°F | 6.0" |
| April | 45°F | 68°F | 56°F | 6.7" |
| May | 55°F | 76°F | 65°F | 6.5" |
| June | 64°F | 84°F | 74°F | 8.6" |
| July | 68°F | 88°F | 78°F | 8.7" |
| August | 66°F | 86°F | 76°F | 7.5" |
| September | 60°F | 80°F | 69°F | 8.6" |
| October | 49°F | 69°F | 58°F | 8.1" |
| November | 38°F | 58°F | 47°F | 7.5" |
| December | 32°F | 50°F | 40°F | 7.1" |
| Index | Morningside | Maryland | National |
| Air quality index | 47 | 43 | 42 |
| Pollution index | 849,185 | 5,342,367 | 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 | 0.010% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Brandywine, MD | 9,269 | 47 | 6.0% |
| Andrews AFB, MD | 3,393 | 47 | 6.0% |
| Glenarden, MD | 6,365 | 47 | 6.0% |
| Marlboro Meadows, MD | 3,836 | 47 | 6.0% |
| Queensland, MD | 1,843 | 47 | 6.0% |
| Morningside, MD | 1,157 | 47 | 6.0% |
| City | Population | Air Quality Index | National Avg. |
| Mammoth Spring, AR | 1,157 | 36 | 28.0% |
| Clay, CA | 1,157 | 52 | 4.0% |
| Parkers Prairie, MN | 1,157 | 29 | 42.0% |
| Cairo, NE | 1,157 | 19 | 62.0% |
| Twin Lakes, NM | 1,157 | 17 | 66.0% |
| Morningside, MD | 1,157 | 47 | 6.0% |