Annex, Oregon has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 39.3 °F (low) to 65 °F (high). Annual precipitation averages 12.3 Inches. Annex is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 22.5 °F | 36.9 °F | 1.75 in. |
| February | 26.2 °F | 45.4 °F | 1.25 in. |
| March | 32.5 °F | 56.6 °F | 1.24 in. |
| April | 37.7 °F | 64.5 °F | 0.94 in. |
| May | 46.1 °F | 74.2 °F | 1.2 in. |
| June | 52.8 °F | 82.5 °F | 0.96 in. |
| July | 60.0 °F | 93.5 °F | 0.28 in. |
| August | 57.2 °F | 92.0 °F | 0.17 in. |
| September | 48.0 °F | 81.3 °F | 0.37 in. |
| October | 37.1 °F | 66.0 °F | 0.74 in. |
| November | 28.6 °F | 49.3 °F | 1.32 in. |
| December | 23.0 °F | 38.2 °F | 2.09 in. |
| Annual | 39.3 °F | 65 °F | 12.31 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |