Farmington, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 35.9 °F (low) to 58.1 °F (high). Annual precipitation averages 24.2 Inches. Farmington is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 25.3 °F | 36.8 °F | 3.21 in. |
| February | 26.0 °F | 40.6 °F | 2.33 in. |
| March | 29.8 °F | 48.1 °F | 2.56 in. |
| April | 34.4 °F | 55.7 °F | 2.05 in. |
| May | 40.5 °F | 65.2 °F | 2.25 in. |
| June | 45.4 °F | 71.0 °F | 1.65 in. |
| July | 48.8 °F | 82.4 °F | 0.62 in. |
| August | 48.6 °F | 83.7 °F | 0.59 in. |
| September | 42.4 °F | 74.1 °F | 0.76 in. |
| October | 35.2 °F | 59.4 °F | 1.98 in. |
| November | 29.8 °F | 44.1 °F | 2.93 in. |
| December | 24.4 °F | 35.5 °F | 3.26 in. |
| Annual | 35.9 °F | 58.1 °F | 24.19 in. |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |