Ashton, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.5 °F (low) to 54.8 °F (high). Annual precipitation averages 18.5 Inches. Ashton is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 10.8 °F | 28.6 °F | 1.99 in. |
| February | 13.9 °F | 32.8 °F | 1.31 in. |
| March | 21.9 °F | 43.1 °F | 1.37 in. |
| April | 29.0 °F | 53.4 °F | 1.83 in. |
| May | 37.0 °F | 64.0 °F | 2.2 in. |
| June | 43.2 °F | 72.3 °F | 1.71 in. |
| July | 48.2 °F | 82.2 °F | 0.65 in. |
| August | 46.5 °F | 81.9 °F | 0.82 in. |
| September | 39.5 °F | 71.8 °F | 1.23 in. |
| October | 30.2 °F | 56.7 °F | 1.69 in. |
| November | 20.8 °F | 40.8 °F | 1.51 in. |
| December | 12.4 °F | 29.4 °F | 2.14 in. |
| Annual | 29.5 °F | 54.8 °F | 18.45 in. |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |