Franklin, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.1 °F (low) to 60.2 °F (high). Annual precipitation averages 17.5 Inches. Franklin is located in USDA Plant Hardiness Zone 6a. 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 | 13.8 °F | 32.4 °F | 1.8 in. |
| February | 17.5 °F | 37.2 °F | 1.52 in. |
| March | 27.0 °F | 49.3 °F | 1.65 in. |
| April | 33.0 °F | 58.4 °F | 1.94 in. |
| May | 40.1 °F | 68.1 °F | 2.35 in. |
| June | 46.4 °F | 79.1 °F | 1.23 in. |
| July | 53.1 °F | 89.3 °F | 0.73 in. |
| August | 51.4 °F | 88.1 °F | 0.75 in. |
| September | 42.9 °F | 77.7 °F | 1.34 in. |
| October | 32.7 °F | 62.7 °F | 1.55 in. |
| November | 24.1 °F | 46.7 °F | 1.25 in. |
| December | 15.6 °F | 33.6 °F | 1.42 in. |
| Annual | 33.1 °F | 60.2 °F | 17.53 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 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |