Warrenton, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 7.2 °C (low) to 14.6 °C (high). Annual precipitation averages 1988.3 Millimeters. 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 | 3.6 °C | 9.4 °C | 304.29 mm |
| February | 3.8 °C | 10.3 °C | 207.01 mm |
| March | 4.2 °C | 11.7 °C | 224.03 mm |
| April | 5.4 °C | 13.3 °C | 162.31 mm |
| May | 7.9 °C | 15.8 °C | 90.42 mm |
| June | 9.9 °C | 17.6 °C | 67.31 mm |
| July | 12.1 °C | 19.6 °C | 23.88 mm |
| August | 12.1 °C | 20.3 °C | 31.24 mm |
| September | 10.7 °C | 19.7 °C | 70.36 mm |
| October | 7.8 °C | 15.9 °C | 179.83 mm |
| November | 5.4 °C | 11.9 °C | 313.94 mm |
| December | 3.4 °C | 9.2 °C | 313.69 mm |
| Annual | 7.2 °C | 14.6 °C | 1988.31 mm |
| 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 : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |