| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 26°F | 39°F | 33°F | 2.3" |
| February | 30°F | 48°F | 38°F | 1.2" |
| March | 35°F | 56°F | 46°F | 1.7" |
| April | 41°F | 65°F | 53°F | 1.6" |
| May | 49°F | 75°F | 62°F | 1.4" |
| June | 56°F | 83°F | 69°F | 2.8" |
| July | 64°F | 93°F | 79°F | 0.7" |
| August | 61°F | 92°F | 77°F | 1.0" |
| September | 53°F | 82°F | 68°F | 1.2" |
| October | 42°F | 64°F | 53°F | 2.1" |
| November | 33°F | 49°F | 41°F | 1.3" |
| December | 25°F | 37°F | 31°F | 1.8" |
| Index | Sunnyside | Washington | National |
| Air quality index | 38 | 36 | 42 |
| Pollution index | 697,942 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 227 |
| Days with moderate air quality | 128 |
| Days w/ poor A.Q. for sensitive groups | 10 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.004% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.010% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Grandview, WA | 11,075 | 37 | 26.0% |
| Prosser, WA | 6,288 | 37 | 26.0% |
| Mabton, WA | 2,192 | 38 | 24.0% |
| Zillah, WA | 3,137 | 38 | 24.0% |
| Buena, WA | 845 | 38 | 24.0% |
| Sunnyside, WA | 16,703 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Highland Village, TX | 16,701 | 51 | 2.0% |
| Farmingville, NY | 16,705 | 43 | 14.0% |
| Cohoes, NY | 16,708 | 37 | 26.0% |
| Sylvan Lake, AB | 16,694 | n/a | |
| Opelousas, LA | 16,687 | 41 | 18.0% |
| Sunnyside, WA | 16,703 | 38 | 24.0% |
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