| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 19°F | 45°F | 31°F | 1.0" |
| February | 22°F | 49°F | 34°F | 1.5" |
| March | 34°F | 62°F | 47°F | 2.6" |
| April | 44°F | 71°F | 57°F | 4.2" |
| May | 53°F | 79°F | 66°F | 5.6" |
| June | 65°F | 89°F | 77°F | 5.5" |
| July | 68°F | 93°F | 80°F | 4.4" |
| August | 66°F | 91°F | 78°F | 5.2" |
| September | 57°F | 84°F | 69°F | 4.4" |
| October | 44°F | 73°F | 57°F | 3.3" |
| November | 33°F | 61°F | 46°F | 1.6" |
| December | 22°F | 46°F | 33°F | 1.8" |
| Index | Denison | Kansas | National |
| Air quality index | 41 | 47 | 42 |
| Pollution index | 308,193 | 989,153 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 294 |
| Days with moderate air quality | 70 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 1 |
| 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. |
| Netawaka, KS | 152 | 41 | 18.0% |
| Holton, KS | 3,233 | 41 | 18.0% |
| Hoyt, KS | 600 | 41 | 18.0% |
| Whiting, KS | 238 | 41 | 18.0% |
| Circleville, KS | 158 | 41 | 18.0% |
| Denison, KS | 104 | 41 | 18.0% |
| City | Population | Air Quality Index | National Avg. |
| Nolic, AZ | 104 | 47 | 6.0% |
| Moffat, CO | 104 | 16 | 68.0% |
| Garber, IA | 104 | 29 | 42.0% |
| Houghton, IA | 104 | 29 | 42.0% |
| St. Donatus, IA | 104 | 29 | 42.0% |
| Denison, KS | 104 | 41 | 18.0% |
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