| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 25°F | 46°F | 34°F | 3.1" |
| February | 25°F | 47°F | 36°F | 2.7" |
| March | 33°F | 58°F | 45°F | 3.6" |
| April | 43°F | 70°F | 56°F | 3.8" |
| May | 52°F | 77°F | 65°F | 4.1" |
| June | 62°F | 86°F | 74°F | 4.7" |
| July | 67°F | 90°F | 78°F | 4.5" |
| August | 65°F | 88°F | 76°F | 4.7" |
| September | 58°F | 82°F | 70°F | 4.3" |
| October | 47°F | 70°F | 58°F | 5.7" |
| November | 36°F | 59°F | 47°F | 2.8" |
| December | 30°F | 50°F | 39°F | 4.3" |
| Index | Pasadena | Maryland | National |
| Air quality index | 46 | 43 | 42 |
| Pollution index | 3,494,010 | 5,342,367 | 2,726,193 |
| 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 | 0.040% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.010% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Arden on the Severn, MD | 1,457 | 46 | 8.0% |
| Crownsville, MD | 1,473 | 46 | 8.0% |
| Herald Harbor, MD | 2,414 | 46 | 8.0% |
| Odenton, MD | 42,258 | 46 | 8.0% |
| Edgemere, MD | 8,652 | 46 | 8.0% |
| Pasadena, MD | 29,432 | 46 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| Stockbridge, GA | 29,446 | 52 | 4.0% |
| Norwood, MA | 29,446 | 43 | 14.0% |
| Oak Park, MI | 29,446 | 56 | 12.0% |
| East Palo Alto, CA | 29,448 | 43 | 14.0% |
| Seguin, TX | 29,458 | 49 | 2.0% |
| Pasadena, MD | 29,432 | 46 | 8.0% |
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