Waterloo, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.8 °F (low) to 63.9 °F (high). Annual precipitation averages 45.4 Inches. Waterloo is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 35.1 °F | 47.6 °F | 6.24 in. |
| February | 35.3 °F | 51.4 °F | 4.82 in. |
| March | 37.6 °F | 56.0 °F | 5.26 in. |
| April | 40.4 °F | 60.9 °F | 4.13 in. |
| May | 45.2 °F | 67.8 °F | 2.87 in. |
| June | 49.4 °F | 73.3 °F | 1.94 in. |
| July | 53.0 °F | 83.3 °F | 0.4 in. |
| August | 52.6 °F | 84.1 °F | 0.51 in. |
| September | 48.7 °F | 77.7 °F | 1.72 in. |
| October | 43.1 °F | 64.9 °F | 3.91 in. |
| November | 38.6 °F | 52.9 °F | 6.49 in. |
| December | 34.9 °F | 46.6 °F | 7.1 in. |
| Annual | 42.8 °F | 63.9 °F | 45.39 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°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 |