Ephrata, Washington has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 4 °C (low) to 16.8 °C (high). Annual precipitation averages 202.2 Millimeters. Ephrata 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.5 °C | 2.2 °C | 24.38 mm |
| February | -2.9 °C | 6.2 °C | 18.03 mm |
| March | -0.2 °C | 11.9 °C | 19.05 mm |
| April | 2.8 °C | 17.1 °C | 17.02 mm |
| May | 7.4 °C | 22.5 °C | 16.51 mm |
| June | 10.8 °C | 26.3 °C | 16.76 mm |
| July | 14.3 °C | 31.4 °C | 7.37 mm |
| August | 13.7 °C | 30.8 °C | 4.57 mm |
| September | 9.2 °C | 25.7 °C | 6.35 mm |
| October | 3.6 °C | 17.2 °C | 17.02 mm |
| November | -1.4 °C | 8.1 °C | 23.62 mm |
| December | -4.6 °C | 2.1 °C | 31.5 mm |
| Annual | 4 °C | 16.8 °C | 202.18 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |