Harrah, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 38.9 °F (low) to 64.2 °F (high). Annual precipitation averages 7.7 Inches. Harrah is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 25.2 °F | 39.2 °F | 1.25 in. |
| February | 27.4 °F | 47.3 °F | 0.78 in. |
| March | 32.3 °F | 56.5 °F | 0.63 in. |
| April | 37.3 °F | 64.2 °F | 0.47 in. |
| May | 45.1 °F | 73.6 °F | 0.67 in. |
| June | 50.5 °F | 80.0 °F | 0.47 in. |
| July | 56.0 °F | 89.0 °F | 0.18 in. |
| August | 54.5 °F | 88.0 °F | 0.19 in. |
| September | 46.7 °F | 79.4 °F | 0.21 in. |
| October | 37.4 °F | 65.0 °F | 0.63 in. |
| November | 29.4 °F | 49.5 °F | 0.8 in. |
| December | 24.4 °F | 38.2 °F | 1.37 in. |
| Annual | 38.9 °F | 64.2 °F | 7.65 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |