Toppenish, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 3.8 °C (low) to 17.8 °C (high). Annual precipitation averages 196.1 Millimeters. Toppenish is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.7 °C | 4.1 °C | 26.67 mm |
| February | -2.7 °C | 8.4 °C | 18.29 mm |
| March | 0.1 °C | 13.6 °C | 14.73 mm |
| April | 2.9 °C | 17.9 °C | 13.21 mm |
| May | 7.2 °C | 23 °C | 19.3 mm |
| June | 10.3 °C | 26.4 °C | 15.24 mm |
| July | 13.3 °C | 31.5 °C | 5.84 mm |
| August | 12.4 °C | 30.9 °C | 5.08 mm |
| September | 8.1 °C | 26.1 °C | 5.59 mm |
| October | 2.9 °C | 18.2 °C | 17.78 mm |
| November | -1.5 °C | 9.7 °C | 23.11 mm |
| December | -4.1 °C | 3.5 °C | 31.24 mm |
| Annual | 3.8 °C | 17.8 °C | 196.08 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |