| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 35°F | 53°F | 43°F | 3.1" |
| February | 36°F | 54°F | 44°F | 2.5" |
| March | 43°F | 62°F | 51°F | 3.5" |
| April | 52°F | 72°F | 61°F | 3.5" |
| May | 61°F | 79°F | 69°F | 4.2" |
| June | 70°F | 87°F | 78°F | 4.9" |
| July | 74°F | 90°F | 81°F | 4.8" |
| August | 73°F | 88°F | 80°F | 6.1" |
| September | 68°F | 83°F | 75°F | 5.7" |
| October | 58°F | 74°F | 65°F | 5.5" |
| November | 46°F | 64°F | 54°F | 3.3" |
| December | 40°F | 57°F | 48°F | 3.5" |
| Index | Portsmouth | Virginia | National |
| Air quality index | 40 | 58 | 42 |
| Pollution index | 2,392,300 | 1,561,881 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 317 |
| Days with moderate air quality | 48 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.110% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.030% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Chesapeake, VA | 242,647 | 40 | 20.0% |
| Hampton, VA | 135,169 | 40 | 20.0% |
| Norfolk, VA | 244,300 | 40 | 20.0% |
| Carrollton, VA | 6,340 | 40 | 20.0% |
| Portsmouth, VA | 94,961 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| South Gate, CA | 94,905 | 72 | 44.0% |
| Roswell, GA | 94,884 | 52 | 4.0% |
| Hesperia, CA | 95,163 | 89 | 78.0% |
| North Vancouver, BC | 94,662 | n/a | |
| Sunrise, FL | 94,657 | 41 | 18.0% |
| Portsmouth, VA | 94,961 | 40 | 20.0% |
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