Waterloo, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6 °C (low) to 17.7 °C (high). Annual precipitation averages 1152.9 Millimeters. 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 | 1.7 °C | 8.7 °C | 158.5 mm |
| February | 1.8 °C | 10.8 °C | 122.43 mm |
| March | 3.1 °C | 13.3 °C | 133.6 mm |
| April | 4.7 °C | 16.1 °C | 104.9 mm |
| May | 7.3 °C | 19.9 °C | 72.9 mm |
| June | 9.7 °C | 22.9 °C | 49.28 mm |
| July | 11.7 °C | 28.5 °C | 10.16 mm |
| August | 11.4 °C | 28.9 °C | 12.95 mm |
| September | 9.3 °C | 25.4 °C | 43.69 mm |
| October | 6.2 °C | 18.3 °C | 99.31 mm |
| November | 3.7 °C | 11.6 °C | 164.85 mm |
| December | 1.6 °C | 8.1 °C | 180.34 mm |
| Annual | 6 °C | 17.7 °C | 1152.91 mm |
| 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 : -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 |