Prospect, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 37.4 °F (low) to 63.8 °F (high). Annual precipitation averages 42 Inches. Prospect is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 29.0 °F | 46.3 °F | 6.34 in. |
| February | 29.5 °F | 50.3 °F | 3.9 in. |
| March | 31.6 °F | 54.5 °F | 4.65 in. |
| April | 34.6 °F | 58.4 °F | 3.96 in. |
| May | 40.1 °F | 67.4 °F | 2.65 in. |
| June | 44.4 °F | 74.7 °F | 1.49 in. |
| July | 49.9 °F | 85.6 °F | 0.62 in. |
| August | 48.8 °F | 85.9 °F | 0.6 in. |
| September | 43.4 °F | 79.9 °F | 1.02 in. |
| October | 36.8 °F | 66.0 °F | 2.99 in. |
| November | 32.4 °F | 51.8 °F | 6.18 in. |
| December | 28.8 °F | 44.9 °F | 7.64 in. |
| Annual | 37.4 °F | 63.8 °F | 42.04 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 8a : 10°F to 15°F |
| Plant Hardiness Zone - 2012 | Zone 8a : 10°F to 15°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |