Steptoe, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 2.6 °C (low) to 15.1 °C (high). Annual precipitation averages 526.8 Millimeters. Steptoe is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.4 °C | 3.1 °C | 68.33 mm |
| February | -2.8 °C | 5.4 °C | 49.53 mm |
| March | -0.7 °C | 9.7 °C | 56.9 mm |
| April | 1.7 °C | 13.9 °C | 46.74 mm |
| May | 5.2 °C | 19.1 °C | 47.24 mm |
| June | 7.9 °C | 22.4 °C | 34.8 mm |
| July | 10.1 °C | 28.8 °C | 12.95 mm |
| August | 9.9 °C | 29.3 °C | 12.19 mm |
| September | 6.3 °C | 23.9 °C | 16 mm |
| October | 2.2 °C | 15.7 °C | 42.42 mm |
| November | -0.9 °C | 7.3 °C | 65.53 mm |
| December | -3.8 °C | 2.4 °C | 74.17 mm |
| Annual | 2.6 °C | 15.1 °C | 526.8 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |