| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 15°F | 32°F | 23°F | 1.0" |
| February | 17°F | 35°F | 25°F | 1.1" |
| March | 30°F | 51°F | 39°F | 2.4" |
| April | 41°F | 64°F | 52°F | 4.8" |
| May | 51°F | 74°F | 62°F | 4.6" |
| June | 62°F | 84°F | 73°F | 6.1" |
| July | 66°F | 86°F | 75°F | 4.7" |
| August | 64°F | 84°F | 73°F | 4.5" |
| September | 55°F | 78°F | 66°F | 3.3" |
| October | 43°F | 65°F | 53°F | 3.3" |
| November | 31°F | 51°F | 40°F | 1.9" |
| December | 19°F | 35°F | 27°F | 1.9" |
| Index | Tiffin | Iowa | National |
| Air quality index | 35 | 39 | 42 |
| Pollution index | 5,075,380 | 1,154,535 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 278 |
| Days with moderate air quality | 86 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.070% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 2.000% |
| Lead | 0.040% |
| Mercury | 0.100% |
| City | Population | Air Quality Index | National Avg. |
| North Liberty, IA | 19,159 | 35 | 30.0% |
| Hills, IA | 870 | 35 | 30.0% |
| Solon, IA | 2,690 | 35 | 30.0% |
| Oxford, IA | 707 | 35 | 30.0% |
| Coralville, IA | 21,630 | 35 | 30.0% |
| Tiffin, IA | 3,779 | 35 | 30.0% |
| City | Population | Air Quality Index | National Avg. |
| Alturas, FL | 3,778 | 36 | 28.0% |
| Rochester, IL | 3,778 | 40 | 20.0% |
| Independence, MN | 3,778 | 46 | 8.0% |
| Mojave, CA | 3,780 | 67 | 34.0% |
| Buckhead, GA | 3,780 | 44 | 12.0% |
| Tiffin, IA | 3,779 | 35 | 30.0% |
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