| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 21°F | 37°F | 28°F | 4.4" |
| February | 22°F | 42°F | 31°F | 3.4" |
| March | 26°F | 48°F | 36°F | 5.0" |
| April | 29°F | 54°F | 40°F | 3.8" |
| May | 34°F | 63°F | 48°F | 3.5" |
| June | 39°F | 71°F | 55°F | 3.0" |
| July | 42°F | 82°F | 63°F | 0.7" |
| August | 40°F | 81°F | 61°F | 0.6" |
| September | 35°F | 73°F | 53°F | 1.5" |
| October | 31°F | 59°F | 43°F | 3.2" |
| November | 27°F | 45°F | 35°F | 4.9" |
| December | 19°F | 35°F | 27°F | 6.4" |
| Index | Cayuse | Oregon | National |
| Air quality index | 38 | 32 | 42 |
| Pollution index | 4,405,170 | 7,156,356 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 286 |
| Days with moderate air quality | 72 |
| Days w/ poor A.Q. for sensitive groups | 6 |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.002% |
| Benzene | 0.130% |
| Carbon Tetrachloride | 0.004% |
| Lead | 0.010% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Weston, OR | 600 | 23 | 54.0% |
| Athena, OR | 1,293 | 38 | 24.0% |
| Helix, OR | 290 | 38 | 24.0% |
| Riverside, OR | 287 | 38 | 24.0% |
| Kirkpatrick, OR | 227 | 38 | 24.0% |
| Cayuse, OR | 62 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Igiugig, AK | 62 | 31 | 38.0% |
| Klukwan, AK | 62 | 20 | 60.0% |
| Whitestone, AK | 62 | 38 | 24.0% |
| Petrey, AL | 62 | 52 | 4.0% |
| Yucca, AZ | 62 | 13 | 74.0% |
| Cayuse, OR | 62 | 38 | 24.0% |