| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 14°F | 30°F | 21°F | 1.4" |
| February | 17°F | 33°F | 24°F | 2.7" |
| March | 31°F | 50°F | 39°F | 3.7" |
| April | 40°F | 63°F | 50°F | 7.2" |
| May | 52°F | 74°F | 62°F | 7.7" |
| June | 62°F | 82°F | 72°F | 7.8" |
| July | 65°F | 85°F | 74°F | 7.6" |
| August | 63°F | 82°F | 72°F | 7.4" |
| September | 54°F | 77°F | 64°F | 7.1" |
| October | 43°F | 64°F | 53°F | 6.9" |
| November | 32°F | 50°F | 40°F | 3.7" |
| December | 20°F | 35°F | 27°F | 5.3" |
| Index | Newton | Iowa | National |
| Air quality index | 39 | 39 | 42 |
| Pollution index | 3,955,060 | 1,154,535 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 306 |
| Days with moderate air quality | 59 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.002% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Collins, IA | 444 | 37 | 26.0% |
| Gilman, IA | 543 | 37 | 26.0% |
| Baxter, IA | 935 | 37 | 26.0% |
| Laurel, IA | 194 | 37 | 26.0% |
| Colfax, IA | 1,886 | 39 | 22.0% |
| Newton, IA | 15,160 | 39 | 22.0% |
| City | Population | Air Quality Index | National Avg. |
| Brooklyn Park, MD | 15,163 | 46 | 8.0% |
| Seaford, NY | 15,153 | 51 | 2.0% |
| Bellair-Meadowbrook Terrace, FL | 15,168 | 43 | 14.0% |
| Graham, NC | 15,168 | 31 | 38.0% |
| Olivehurst, CA | 15,149 | 44 | 12.0% |
| Newton, IA | 15,160 | 39 | 22.0% |
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