Ashton, Idaho has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.4 °C (low) to 12.6 °C (high). Annual precipitation averages 468.6 Millimeters. 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 | -11.8 °C | -1.9 °C | 50.55 mm |
| February | -10.1 °C | 0.4 °C | 33.27 mm |
| March | -5.6 °C | 6.2 °C | 34.8 mm |
| April | -1.7 °C | 11.9 °C | 46.48 mm |
| May | 2.8 °C | 17.8 °C | 55.88 mm |
| June | 6.2 °C | 22.4 °C | 43.43 mm |
| July | 9 °C | 27.9 °C | 16.51 mm |
| August | 8.1 °C | 27.7 °C | 20.83 mm |
| September | 4.2 °C | 22.1 °C | 31.24 mm |
| October | -1 °C | 13.7 °C | 42.93 mm |
| November | -6.2 °C | 4.9 °C | 38.35 mm |
| December | -10.9 °C | -1.4 °C | 54.36 mm |
| Annual | -1.4 °C | 12.6 °C | 468.63 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |