Monroe, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 5.7 °C (low) to 17.4 °C (high). Annual precipitation averages 1148.3 Millimeters. 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 | 1.7 °C | 8.5 °C | 178.05 mm |
| February | 1.7 °C | 10.6 °C | 137.41 mm |
| March | 2.8 °C | 13.2 °C | 157.73 mm |
| April | 4.3 °C | 15.8 °C | 86.87 mm |
| May | 6.9 °C | 19.4 °C | 54.1 mm |
| June | 9.1 °C | 23 °C | 32.51 mm |
| July | 11.1 °C | 27.8 °C | 6.86 mm |
| August | 11 °C | 28.2 °C | 10.67 mm |
| September | 8.9 °C | 25 °C | 30.48 mm |
| October | 5.8 °C | 17.9 °C | 84.84 mm |
| November | 3.3 °C | 11.6 °C | 153.42 mm |
| December | 1.4 °C | 7.9 °C | 215.39 mm |
| Annual | 5.7 °C | 17.4 °C | 1148.33 mm |
| 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 : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |