Happy Valley, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 43.2 °F (low) to 62.4 °F (high). Annual precipitation averages 49.4 Inches. Happy Valley is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 35.0 °F | 45.9 °F | 6.7 in. |
| February | 35.4 °F | 49.5 °F | 4.79 in. |
| March | 37.5 °F | 54.4 °F | 5.53 in. |
| April | 40.4 °F | 60.3 °F | 4.13 in. |
| May | 45.4 °F | 67.9 °F | 3.47 in. |
| June | 49.6 °F | 72.9 °F | 2.31 in. |
| July | 53.3 °F | 81.0 °F | 0.61 in. |
| August | 53.7 °F | 81.7 °F | 0.57 in. |
| September | 50.1 °F | 75.4 °F | 1.97 in. |
| October | 44.5 °F | 63.0 °F | 4.74 in. |
| November | 39.0 °F | 51.7 °F | 7.07 in. |
| December | 34.7 °F | 45.2 °F | 7.48 in. |
| Annual | 43.2 °F | 62.4 °F | 49.37 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 30-40 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 | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |