| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 44°F | 30°F | 1.5" |
| February | 21°F | 47°F | 33°F | 2.9" |
| March | 32°F | 61°F | 45°F | 2.9" |
| April | 41°F | 69°F | 53°F | 3.7" |
| May | 51°F | 78°F | 63°F | 7.7" |
| June | 63°F | 90°F | 76°F | 5.8" |
| July | 67°F | 94°F | 80°F | 8.4" |
| August | 65°F | 91°F | 77°F | 6.1" |
| September | 57°F | 83°F | 68°F | 4.1" |
| October | 43°F | 71°F | 55°F | 5.4" |
| November | 31°F | 58°F | 42°F | 3.8" |
| December | 20°F | 43°F | 30°F | 3.5" |
| Index | Hays | Kansas | National |
| Air quality index | 15 | 47 | 42 |
| Pollution index | 95,096 | 989,153 | 2,726,193 |
| Measurement | Total |
| Days measured | 304 |
| Days with good air quality | 301 |
| Days with moderate air quality | 3 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.005% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Schoenchen, KS | 202 | 15 | 70.0% |
| Catharine, KS | 126 | 15 | 70.0% |
| Ellis, KS | 2,290 | 15 | 70.0% |
| Munjor, KS | 78 | 15 | 70.0% |
| Victoria, KS | 1,115 | 15 | 70.0% |
| Hays, KS | 21,398 | 15 | 70.0% |
| City | Population | Air Quality Index | National Avg. |
| Thorold, ON | 21,396 | n/a | |
| Saint-Lazare, QC | 21,394 | n/a | |
| Cranbrook, BC | 21,392 | n/a | |
| Gardner, MA | 21,410 | 40 | 20.0% |
| Green Valley, AZ | 21,416 | 47 | 6.0% |
| Hays, KS | 21,398 | 15 | 70.0% |