Winchester Bay, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 44.9 °F (low) to 60.1 °F (high). Annual precipitation averages 68.5 Inches. Winchester Bay is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 11 - Feb. 20 through the first frost around Dec. 11 - Dec. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 39.6 °F | 52.8 °F | 9.95 in. |
| February | 39.5 °F | 54.2 °F | 8.15 in. |
| March | 40.4 °F | 55.2 °F | 8.5 in. |
| April | 42.3 °F | 57.2 °F | 6.19 in. |
| May | 46.1 °F | 61.1 °F | 3.99 in. |
| June | 49.7 °F | 64.6 °F | 2.47 in. |
| July | 52.1 °F | 68.0 °F | 0.5 in. |
| August | 51.9 °F | 68.3 °F | 0.61 in. |
| September | 49.7 °F | 68.1 °F | 1.72 in. |
| October | 46.4 °F | 63.3 °F | 4.74 in. |
| November | 42.3 °F | 56.4 °F | 9.84 in. |
| December | 39.1 °F | 52.1 °F | 11.86 in. |
| Annual | 44.9 °F | 60.1 °F | 68.52 in. |
| Average First Frost Date | Dec. 11 - Dec. 20 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9b : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 9a : 20°F to 25°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |