| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 28°F | 43°F | 34°F | 1.3" |
| February | 30°F | 47°F | 37°F | 0.4" |
| March | 37°F | 57°F | 46°F | 1.8" |
| April | 47°F | 69°F | 57°F | 0.8" |
| May | 56°F | 76°F | 65°F | 2.5" |
| June | 64°F | 84°F | 73°F | 0.1" |
| July | 68°F | 89°F | 77°F | 5.9" |
| August | 66°F | 86°F | 75°F | 2.6" |
| September | 60°F | 80°F | 69°F | 4.2" |
| October | 49°F | 69°F | 57°F | 2.4" |
| November | 38°F | 57°F | 46°F | 0.9" |
| December | 33°F | 48°F | 40°F | 0.6" |
| Index | Upper Marlboro | 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. |
| Chesapeake Beach, MD | 6,159 | 41 | 18.0% |
| North Beach, MD | 2,852 | 41 | 18.0% |
| Crownsville, MD | 1,506 | 46 | 8.0% |
| Annapolis, MD | 40,873 | 46 | 8.0% |
| Naval Academy, MD | 5,811 | 46 | 8.0% |
| Upper Marlboro, MD | 601 | 47 | 6.0% |
| City | Population | Air Quality Index | National Avg. |
| Fields Landing, CA | 601 | 27 | 46.0% |
| Fort Jones, CA | 601 | 36 | 28.0% |
| Menlo, GA | 601 | 40 | 20.0% |
| Whitesburg, GA | 601 | 52 | 4.0% |
| Kooskia, ID | 601 | 29 | 42.0% |
| Upper Marlboro, MD | 601 | 47 | 6.0% |