Fernwood, Idaho has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 35.1 °F (low) to 57.7 °F (high). Annual precipitation averages 34.7 Inches. Fernwood 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 | 24.7 °F | 36.0 °F | 4.72 in. |
| February | 24.9 °F | 39.6 °F | 3.53 in. |
| March | 28.5 °F | 47.5 °F | 3.78 in. |
| April | 33.7 °F | 55.6 °F | 2.65 in. |
| May | 39.7 °F | 66.4 °F | 3.05 in. |
| June | 44.9 °F | 72.2 °F | 2.28 in. |
| July | 48.3 °F | 83.0 °F | 0.81 in. |
| August | 47.6 °F | 83.8 °F | 0.81 in. |
| September | 41.4 °F | 73.8 °F | 0.93 in. |
| October | 34.6 °F | 57.7 °F | 2.91 in. |
| November | 29.1 °F | 42.6 °F | 4.24 in. |
| December | 23.5 °F | 34.4 °F | 4.97 in. |
| Annual | 35.1 °F | 57.7 °F | 34.68 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 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 |