Dexter, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.4 °F (low) to 63.1 °F (high). Annual precipitation averages 45.4 Inches. Dexter is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 34.7 °F | 47.9 °F | 5.92 in. |
| February | 35.1 °F | 51.7 °F | 4.75 in. |
| March | 36.9 °F | 56.1 °F | 5.15 in. |
| April | 39.8 °F | 60.1 °F | 4.42 in. |
| May | 44.4 °F | 66.7 °F | 3.24 in. |
| June | 48.5 °F | 72.3 °F | 1.84 in. |
| July | 52.3 °F | 80.8 °F | 0.45 in. |
| August | 51.9 °F | 81.6 °F | 0.47 in. |
| September | 48.4 °F | 76.2 °F | 1.57 in. |
| October | 43.1 °F | 64.5 °F | 3.63 in. |
| November | 38.5 °F | 53.1 °F | 6.75 in. |
| December | 34.6 °F | 46.6 °F | 7.18 in. |
| Annual | 42.4 °F | 63.1 °F | 45.37 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |