| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 28°F | 46°F | 37°F | 2.9" |
| February | 28°F | 48°F | 38°F | 2.3" |
| March | 36°F | 57°F | 46°F | 3.1" |
| April | 45°F | 68°F | 56°F | 3.5" |
| May | 54°F | 77°F | 65°F | 3.1" |
| June | 64°F | 85°F | 74°F | 5.6" |
| July | 69°F | 89°F | 78°F | 4.5" |
| August | 67°F | 87°F | 76°F | 4.8" |
| September | 61°F | 81°F | 70°F | 4.7" |
| October | 50°F | 71°F | 60°F | 4.4" |
| November | 39°F | 60°F | 49°F | 2.9" |
| December | 33°F | 52°F | 42°F | 3.6" |
| Index | Lewes | Delaware | National |
| Air quality index | 36 | 41 | 42 |
| Pollution index | 7,219,540 | 7,274,307 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 303 |
| Days with moderate air quality | 61 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.060% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.030% |
| Mercury | 0.110% |
| City | Population | Air Quality Index | National Avg. |
| Georgetown, DE | 7,436 | 36 | 28.0% |
| Milton, DE | 2,993 | 36 | 28.0% |
| Henlopen Acres, DE | 187 | 36 | 28.0% |
| Rehoboth Beach, DE | 1,588 | 36 | 28.0% |
| Long Neck, DE | 2,869 | 36 | 28.0% |
| Lewes, DE | 3,266 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| North Brooksville, FL | 3,266 | 30 | 40.0% |
| Harlem, GA | 3,267 | 47 | 6.0% |
| McChord AFB, WA | 3,268 | 30 | 40.0% |
| Alexander, AR | 3,263 | 45 | 10.0% |
| Newburgh, IN | 3,263 | 45 | 10.0% |
| Lewes, DE | 3,266 | 36 | 28.0% |
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