Warrenton, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 45 °F (low) to 58.2 °F (high). Annual precipitation averages 78.3 Inches. Warrenton is located in USDA Plant Hardiness Zone 9a. 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 | 38.5 °F | 49.0 °F | 11.98 in. |
| February | 38.9 °F | 50.6 °F | 8.15 in. |
| March | 39.6 °F | 53.1 °F | 8.82 in. |
| April | 41.7 °F | 56.0 °F | 6.39 in. |
| May | 46.2 °F | 60.4 °F | 3.56 in. |
| June | 49.9 °F | 63.6 °F | 2.65 in. |
| July | 53.7 °F | 67.2 °F | 0.94 in. |
| August | 53.7 °F | 68.6 °F | 1.23 in. |
| September | 51.2 °F | 67.5 °F | 2.77 in. |
| October | 46.1 °F | 60.7 °F | 7.08 in. |
| November | 41.8 °F | 53.4 °F | 12.36 in. |
| December | 38.1 °F | 48.6 °F | 12.35 in. |
| Annual | 45 °F | 58.2 °F | 78.28 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 9a : 20°F to 25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |