| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 30°F | 46°F | 37°F | 5.9" |
| February | 26°F | 41°F | 33°F | 2.7" |
| March | 35°F | 53°F | 42°F | 8.4" |
| April | 44°F | 63°F | 52°F | 13.3" |
| May | 52°F | 72°F | 61°F | 6.7" |
| June | 65°F | 82°F | 73°F | 10.2" |
| July | 69°F | 85°F | 77°F | 6.5" |
| August | 70°F | 86°F | 77°F | 8.9" |
| September | 62°F | 82°F | 71°F | 4.4" |
| October | 54°F | 71°F | 61°F | 16.4" |
| November | 41°F | 58°F | 48°F | 6.6" |
| December | 31°F | 46°F | 37°F | 5.9" |
| Index | Viola | Delaware | National |
| Air quality index | 42 | 41 | 42 |
| Pollution index | 3,193,180 | 7,274,307 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 293 |
| Days with moderate air quality | 72 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.010% |
| Mercury | 0.020% |
| City | Population | Air Quality Index | National Avg. |
| Williston, MD | 174 | 36 | 28.0% |
| Farmington, DE | 184 | 36 | 28.0% |
| Denton, MD | 4,488 | 36 | 28.0% |
| West Denton, MD | 14 | 36 | 28.0% |
| Dover Base Housing, DE | 3,620 | 42 | 16.0% |
| Viola, DE | 173 | 42 | 16.0% |
| City | Population | Air Quality Index | National Avg. |
| Chickaloon, AK | 173 | 31 | 38.0% |
| Tanana, AK | 173 | 38 | 24.0% |
| Riverview, AL | 173 | 41 | 18.0% |
| Bodcaw, AR | 173 | 39 | 22.0% |
| Houston, AR | 173 | 45 | 10.0% |
| Viola, DE | 173 | 42 | 16.0% |
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