South Prairie, Washington has a Temperate Oceanic Climate climate (Köppen classification: Cfb). Average annual temperatures range from 42.8 °F (low) to 60.5 °F (high). Annual precipitation averages 48.3 Inches. 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 | 34.8 °F | 46.6 °F | 6.35 in. |
| February | 34.5 °F | 49.3 °F | 4.47 in. |
| March | 36.7 °F | 53.5 °F | 5.22 in. |
| April | 40.0 °F | 58.4 °F | 4.26 in. |
| May | 45.5 °F | 65.5 °F | 3.09 in. |
| June | 50.1 °F | 69.8 °F | 2.66 in. |
| July | 53.5 °F | 76.7 °F | 1.08 in. |
| August | 53.6 °F | 77.5 °F | 1.32 in. |
| September | 49.4 °F | 71.4 °F | 2.02 in. |
| October | 43.2 °F | 60.3 °F | 4.8 in. |
| November | 37.8 °F | 51.2 °F | 7.0 in. |
| December | 34.0 °F | 45.5 °F | 6.07 in. |
| Annual | 42.8 °F | 60.5 °F | 48.34 in. |
| 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 : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfb - Temperate Oceanic Climate |