South Prairie, Washington has a Temperate Oceanic Climate climate (Köppen classification: Cfb). Average annual temperatures range from 6 °C (low) to 15.8 °C (high). Annual precipitation averages 1227.8 Millimeters. South Prairie is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.6 °C | 8.1 °C | 161.29 mm |
| February | 1.4 °C | 9.6 °C | 113.54 mm |
| March | 2.6 °C | 11.9 °C | 132.59 mm |
| April | 4.4 °C | 14.7 °C | 108.2 mm |
| May | 7.5 °C | 18.6 °C | 78.49 mm |
| June | 10.1 °C | 21 °C | 67.56 mm |
| July | 11.9 °C | 24.8 °C | 27.43 mm |
| August | 12 °C | 25.3 °C | 33.53 mm |
| September | 9.7 °C | 21.9 °C | 51.31 mm |
| October | 6.2 °C | 15.7 °C | 121.92 mm |
| November | 3.2 °C | 10.7 °C | 177.8 mm |
| December | 1.1 °C | 7.5 °C | 154.18 mm |
| Annual | 6 °C | 15.8 °C | 1227.84 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| 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 | Cfb - Temperate Oceanic Climate |