Winchester Bay, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 7.2 °C (low) to 15.6 °C (high). Annual precipitation averages 1740.4 Millimeters. 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 | 4.2 °C | 11.6 °C | 252.73 mm |
| February | 4.2 °C | 12.3 °C | 207.01 mm |
| March | 4.7 °C | 12.9 °C | 215.9 mm |
| April | 5.7 °C | 14 °C | 157.23 mm |
| May | 7.8 °C | 16.2 °C | 101.35 mm |
| June | 9.8 °C | 18.1 °C | 62.74 mm |
| July | 11.2 °C | 20 °C | 12.7 mm |
| August | 11.1 °C | 20.2 °C | 15.49 mm |
| September | 9.8 °C | 20.1 °C | 43.69 mm |
| October | 8 °C | 17.4 °C | 120.4 mm |
| November | 5.7 °C | 13.6 °C | 249.94 mm |
| December | 3.9 °C | 11.2 °C | 301.24 mm |
| Annual | 7.2 °C | 15.6 °C | 1740.42 mm |
| 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 : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |