Forest Grove, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 43.3 °F (low) to 63 °F (high). Annual precipitation averages 44.1 Inches. Forest Grove is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 35.0 °F | 46.7 °F | 7.04 in. |
| February | 35.1 °F | 50.6 °F | 5.06 in. |
| March | 37.5 °F | 55.5 °F | 4.76 in. |
| April | 40.5 °F | 60.7 °F | 3.26 in. |
| May | 46.1 °F | 68.1 °F | 2.08 in. |
| June | 50.4 °F | 73.1 °F | 1.3 in. |
| July | 54.5 °F | 81.2 °F | 0.3 in. |
| August | 54.3 °F | 82.0 °F | 0.47 in. |
| September | 50.0 °F | 76.2 °F | 1.28 in. |
| October | 43.6 °F | 63.8 °F | 3.55 in. |
| November | 38.4 °F | 52.4 °F | 6.63 in. |
| December | 34.6 °F | 45.8 °F | 8.36 in. |
| Annual | 43.3 °F | 63 °F | 44.09 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 50-75 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 |