| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 12°F | 30°F | 21°F | 0.8" |
| February | 14°F | 34°F | 23°F | 1.0" |
| March | 28°F | 49°F | 37°F | 2.2" |
| April | 39°F | 63°F | 49°F | 4.1" |
| May | 49°F | 73°F | 60°F | 5.2" |
| June | 60°F | 83°F | 71°F | 7.1" |
| July | 64°F | 86°F | 75°F | 4.2" |
| August | 62°F | 83°F | 71°F | 5.5" |
| September | 53°F | 77°F | 63°F | 2.8" |
| October | 41°F | 64°F | 51°F | 4.0" |
| November | 28°F | 49°F | 38°F | 3.7" |
| December | 16°F | 33°F | 24°F | 2.5" |
| Index | Granville | Iowa | National |
| Air quality index | 35 | 39 | 50 |
| Pollution index | 890,079 | 1,643,836 | 5,066,862 |
| 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 | 0.004% |
| Mercury | 0.000% |
| City, State | Population | Air Quality Index | National Avg. |
| Alton, IA | 1,325 | 35 | 30% |
| Orange City, IA | 6,153 | 35 | 30% |
| Archer, IA | 177 | 35 | 30% |
| Primghar, IA | 973 | 35 | 30% |
| Le Mars, IA | 9,826 | 35 | 30% |
| Granville, IA | 362 | 35 | 30% |
| City, State | Population | Air Quality Index | National Avg. |
| San Lucas, CA | 362 | 37 | 26% |
| Ballard, CA | 362 | 44 | 12% |
| Bullhead, SD | 362 | 36 | 28% |
| Johnson Village, CO | 362 | 16 | 68% |
| Eunola, AL | 362 | 35 | 30% |
| Granville, IA | 362 | 35 | 30% |
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