Grand Ronde, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.6 °F (low) to 62.8 °F (high). Annual precipitation averages 63 Inches. Grand Ronde 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 | 35.3 °F | 46.7 °F | 10.16 in. |
| February | 35.4 °F | 50.5 °F | 7.45 in. |
| March | 37.3 °F | 54.9 °F | 6.77 in. |
| April | 39.7 °F | 60.4 °F | 5.07 in. |
| May | 44.6 °F | 67.7 °F | 2.71 in. |
| June | 48.6 °F | 72.7 °F | 1.73 in. |
| July | 52.0 °F | 80.3 °F | 0.28 in. |
| August | 52.2 °F | 81.3 °F | 0.42 in. |
| September | 49.2 °F | 76.4 °F | 1.75 in. |
| October | 43.7 °F | 63.9 °F | 5.08 in. |
| November | 38.5 °F | 52.3 °F | 9.65 in. |
| December | 34.7 °F | 45.9 °F | 11.92 in. |
| Annual | 42.6 °F | 62.8 °F | 62.99 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |