| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 13°F | 27°F | 19°F | 0.5" |
| February | 14°F | 29°F | 21°F | 0.4" |
| March | 29°F | 45°F | 36°F | 1.5" |
| April | 40°F | 59°F | 48°F | 3.4" |
| May | 50°F | 70°F | 60°F | 2.9" |
| June | 61°F | 79°F | 69°F | 4.3" |
| July | 65°F | 82°F | 73°F | 3.9" |
| August | 62°F | 79°F | 70°F | 4.0" |
| September | 54°F | 73°F | 63°F | 3.4" |
| October | 43°F | 61°F | 51°F | 3.0" |
| November | 31°F | 47°F | 38°F | 1.0" |
| December | 18°F | 31°F | 24°F | 0.9" |
| Index | Clermont | Iowa | National |
| Air quality index | 39 | 39 | 42 |
| Pollution index | 530,484 | 1,154,535 | 2,726,193 |
| Measurement | Total |
| Days measured | 363 |
| Days with good air quality | 286 |
| Days with moderate air quality | 77 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.002% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| St. Olaf, IA | 134 | 29 | 42.0% |
| Elkader, IA | 1,404 | 29 | 42.0% |
| Farmersburg, IA | 380 | 29 | 42.0% |
| Monona, IA | 1,686 | 29 | 42.0% |
| Castalia, IA | 172 | 35 | 30.0% |
| Clermont, IA | 499 | 39 | 22.0% |
| City | Population | Air Quality Index | National Avg. |
| Subiaco, AR | 499 | 36 | 28.0% |
| Downieville-Lawson-Dumont, CO | 499 | 47 | 6.0% |
| Otho, IA | 499 | 37 | 26.0% |
| Manilla, IN | 499 | 28 | 44.0% |
| Beaver City, NE | 499 | 19 | 62.0% |
| Clermont, IA | 499 | 39 | 22.0% |