Monroe, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.2 °F (low) to 63.3 °F (high). Annual precipitation averages 45.2 Inches. Monroe 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 | 35.0 °F | 47.3 °F | 7.01 in. |
| February | 35.1 °F | 51.1 °F | 5.41 in. |
| March | 37.1 °F | 55.8 °F | 6.21 in. |
| April | 39.8 °F | 60.4 °F | 3.42 in. |
| May | 44.4 °F | 67.0 °F | 2.13 in. |
| June | 48.4 °F | 73.4 °F | 1.28 in. |
| July | 52.0 °F | 82.0 °F | 0.27 in. |
| August | 51.8 °F | 82.8 °F | 0.42 in. |
| September | 48.1 °F | 77.0 °F | 1.2 in. |
| October | 42.4 °F | 64.2 °F | 3.34 in. |
| November | 38.0 °F | 52.8 °F | 6.04 in. |
| December | 34.6 °F | 46.3 °F | 8.48 in. |
| Annual | 42.2 °F | 63.3 °F | 45.21 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 40-50 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 | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |