| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | -26°F | 59°F | 23°F | n/a |
| February | -17°F | 59°F | 23°F | n/a |
| March | -4°F | 82°F | 38°F | n/a |
| April | 18°F | 91°F | 50°F | n/a |
| May | 32°F | 91°F | 62°F | n/a |
| June | 45°F | 95°F | 71°F | n/a |
| July | 46°F | 102°F | 75°F | n/a |
| August | 41°F | 97°F | 72°F | n/a |
| September | 32°F | 90°F | 63°F | n/a |
| October | 23°F | 88°F | 50°F | n/a |
| November | 7°F | 81°F | 40°F | n/a |
| December | -13°F | 57°F | 24°F | n/a |
| Index | Marcus | Iowa | National |
| Air quality index | 41 | 39 | 50 |
| Pollution index | 890,079 | 1,643,836 | 5,066,862 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 254 |
| Days with moderate air quality | 110 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.004% |
| Mercury | 0.000% |
| City, State | Population | Air Quality Index | National Avg. |
| Calumet, IA | 192 | 41 | 18% |
| Larrabee, IA | 202 | 41 | 18% |
| Paullina, IA | 1,034 | 41 | 18% |
| Cherokee, IA | 5,113 | 41 | 18% |
| Meriden, IA | 209 | 41 | 18% |
| Marcus, IA | 1,146 | 41 | 18% |
| City, State | Population | Air Quality Index | National Avg. |
| Edison, GA | 1,146 | 43 | 14% |
| Summerland, CA | 1,146 | 44 | 12% |
| Rome City, IN | 1,146 | 47 | 6% |
| Holly Pond, AL | 1,146 | 37 | 26% |
| Plattekill, NY | 1,146 | 36 | 28% |
| Marcus, IA | 1,146 | 41 | 18% |