| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 32°F | 44°F | 37°F | 2.7" |
| February | 32°F | 45°F | 38°F | 2.7" |
| March | 40°F | 55°F | 47°F | 3.4" |
| April | 51°F | 68°F | 59°F | 3.8" |
| May | 60°F | 76°F | 67°F | 3.9" |
| June | 70°F | 86°F | 77°F | 4.5" |
| July | 75°F | 90°F | 82°F | 5.0" |
| August | 73°F | 87°F | 79°F | 4.6" |
| September | 67°F | 80°F | 73°F | 4.4" |
| October | 55°F | 69°F | 62°F | 4.6" |
| November | 45°F | 58°F | 50°F | 2.4" |
| December | 37°F | 48°F | 42°F | 4.1" |
| Index | Roland Parl-Homewood-Guilford | Baltimore | Maryland |
| Air quality index | 46 | 46 | 43 |
| Pollution index | 9,823,920 | 9,823,920 | 5,342,367 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 223 |
| Days with moderate air quality | 129 |
| Days w/ poor A.Q. for sensitive groups | 13 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.050% |
| Lead | 0.030% |
| Mercury | 0.140% |
| City | Population | Air Quality Index | National Avg. |
| Rossville, MD | 15,993 | 46 | 8.0% |
| Cockeysville, MD | 22,602 | 46 | 8.0% |
| Mays Chapel, MD | 12,229 | 46 | 8.0% |
| Reisterstown, MD | 27,804 | 46 | 8.0% |
| Edgemere, MD | 8,652 | 46 | 8.0% |
| Baltimore, MD | 602,274 | 46 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| Milwaukee, WI | 592,649 | 44 | 12.0% |
| Louisville, KY | 618,733 | 49 | 2.0% |
| Albuquerque, NM | 560,447 | 53 | 6.0% |
| Surrey, BC | 560,150 | n/a | |
| Las Vegas, NV | 644,594 | 54 | 8.0% |
| Baltimore, MD | 602,274 | 46 | 8.0% |
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