| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 10°F | 33°F | 21°F | 0.7" |
| February | 13°F | 38°F | 24°F | 0.8" |
| March | 26°F | 53°F | 38°F | 1.5" |
| April | 37°F | 66°F | 51°F | 3.5" |
| May | 48°F | 77°F | 62°F | 4.2" |
| June | 59°F | 86°F | 72°F | 4.9" |
| July | 63°F | 89°F | 76°F | 3.5" |
| August | 60°F | 86°F | 73°F | 5.6" |
| September | 51°F | 81°F | 65°F | 3.1" |
| October | 38°F | 68°F | 52°F | 3.0" |
| November | 25°F | 53°F | 38°F | 1.1" |
| December | 13°F | 36°F | 24°F | 1.7" |
| Index | Merrill | Iowa | National |
| Air quality index | 35 | 39 | 42 |
| Pollution index | 731,145 | 1,154,535 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 322 |
| Days with moderate air quality | 42 |
| 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 | 0.002% |
| Lead | 0.002% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Chatsworth, IA | 56 | 35 | 30.0% |
| Struble, IA | 95 | 35 | 30.0% |
| Kingsley, IA | 1,459 | 35 | 30.0% |
| Craig, IA | 42 | 35 | 30.0% |
| Brunsville, IA | 140 | 35 | 30.0% |
| Merrill, IA | 1,016 | 35 | 30.0% |
| City | Population | Air Quality Index | National Avg. |
| Burrton, KS | 1,016 | 40 | 20.0% |
| Mount Vernon, MD | 1,016 | 41 | 18.0% |
| New Franklin, MO | 1,016 | 38 | 24.0% |
| Greene, RI | 1,016 | 44 | 12.0% |
| Hewitt, WI | 1,016 | 34 | 32.0% |
| Merrill, IA | 1,016 | 35 | 30.0% |
Here are the best places to live in Iowa
See the best places to live in Merrill
Check out the 10 most dangerous cities in Iowa
Most Dangerous Cities In The US