Yoncalla, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6 °C (low) to 18.6 °C (high). Annual precipitation averages 1116.1 Millimeters. Yoncalla is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2 °C | 9.6 °C | 170.69 mm |
| February | 2.2 °C | 11.8 °C | 122.94 mm |
| March | 3.1 °C | 14.4 °C | 125.98 mm |
| April | 4.6 °C | 17 °C | 93.22 mm |
| May | 7.1 °C | 20.9 °C | 67.82 mm |
| June | 9.3 °C | 23.7 °C | 31.24 mm |
| July | 11.5 °C | 29 °C | 8.38 mm |
| August | 11.2 °C | 29.5 °C | 10.16 mm |
| September | 9 °C | 26.6 °C | 29.46 mm |
| October | 6.2 °C | 19.6 °C | 80.26 mm |
| November | 4.1 °C | 12.4 °C | 167.13 mm |
| December | 1.9 °C | 8.8 °C | 208.79 mm |
| Annual | 6 °C | 18.6 °C | 1116.07 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |