| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 37°F | 26°F | 2.5" |
| February | 20°F | 40°F | 28°F | 1.3" |
| March | 33°F | 55°F | 42°F | 4.6" |
| April | 43°F | 66°F | 53°F | 6.5" |
| May | 53°F | 75°F | 63°F | 6.9" |
| June | 64°F | 85°F | 73°F | 6.7" |
| July | 67°F | 87°F | 76°F | 7.0" |
| August | 65°F | 84°F | 74°F | 6.5" |
| September | 56°F | 79°F | 66°F | 7.2" |
| October | 45°F | 67°F | 54°F | 7.1" |
| November | 32°F | 54°F | 42°F | 4.5" |
| December | 21°F | 39°F | 29°F | 4.8" |
| Index | Hepburn | Iowa | National |
| Air quality index | 40 | 39 | 42 |
| Pollution index | 338,773 | 1,154,535 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 283 |
| Days with moderate air quality | 82 |
| 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 | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Essex, IA | 772 | 40 | 20.0% |
| Red Oak, IA | 5,323 | 40 | 20.0% |
| Stanton, IA | 627 | 40 | 20.0% |
| Clarinda, IA | 5,371 | 40 | 20.0% |
| Carbon, IA | 52 | 40 | 20.0% |
| Hepburn, IA | 10 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Memphis, AL | 10 | 35 | 30.0% |
| Indian Falls, CA | 10 | 46 | 8.0% |
| Bolan, IA | 10 | 15 | 70.0% |
| Jacksonville, IA | 10 | 40 | 20.0% |
| Bassett, KS | 10 | 22 | 56.0% |
| Hepburn, IA | 10 | 40 | 20.0% |
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