South Bend, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.4 °C (low) to 15.4 °C (high). Annual precipitation averages 2115.1 Millimeters. South Bend is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.9 °C | 9.2 °C | 329.69 mm |
| February | 2.4 °C | 10.4 °C | 207.52 mm |
| March | 3.3 °C | 11.9 °C | 239.01 mm |
| April | 4.7 °C | 14.4 °C | 173.48 mm |
| May | 7.4 °C | 17.4 °C | 92.96 mm |
| June | 9.7 °C | 19.3 °C | 71.37 mm |
| July | 11.5 °C | 21.6 °C | 28.19 mm |
| August | 11.4 °C | 22.4 °C | 38.1 mm |
| September | 9.7 °C | 21.1 °C | 75.44 mm |
| October | 6.7 °C | 16.4 °C | 202.95 mm |
| November | 4.1 °C | 11.7 °C | 325.12 mm |
| December | 2.6 °C | 8.8 °C | 331.22 mm |
| Annual | 6.4 °C | 15.4 °C | 2115.05 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°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 |