Bay City, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.8 °C (low) to 14.6 °C (high). Annual precipitation averages 2235.5 Millimeters. Bay City is located in USDA Plant Hardiness Zone 9a. 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 | 3.8 °C | 10.2 °C | 317.25 mm |
| February | 3.6 °C | 10.9 °C | 239.01 mm |
| March | 4.1 °C | 11.9 °C | 248.16 mm |
| April | 5.1 °C | 13.3 °C | 189.23 mm |
| May | 7.4 °C | 15.4 °C | 115.06 mm |
| June | 9.6 °C | 17.2 °C | 82.8 mm |
| July | 11 °C | 19.2 °C | 24.64 mm |
| August | 11.1 °C | 19.7 °C | 33.02 mm |
| September | 9.6 °C | 19.2 °C | 78.99 mm |
| October | 7.4 °C | 16 °C | 203.2 mm |
| November | 5.2 °C | 12.3 °C | 332.23 mm |
| December | 3.6 °C | 9.8 °C | 371.86 mm |
| Annual | 6.8 °C | 14.6 °C | 2235.45 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |