Iona, Idaho has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -0.4 °C (low) to 13.9 °C (high). Annual precipitation averages 309.4 Millimeters. Iona is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.1 °C | -1.7 °C | 27.94 mm |
| February | -9.3 °C | 1 °C | 19.3 mm |
| March | -4 °C | 8.1 °C | 25.91 mm |
| April | -0.6 °C | 13.8 °C | 30.48 mm |
| May | 3.7 °C | 18.9 °C | 44.45 mm |
| June | 7.3 °C | 23.8 °C | 30.73 mm |
| July | 10.4 °C | 29.6 °C | 14.22 mm |
| August | 9.3 °C | 29.3 °C | 16.51 mm |
| September | 5.2 °C | 23.5 °C | 25.4 mm |
| October | -0.2 °C | 15.3 °C | 28.19 mm |
| November | -5.4 °C | 6.1 °C | 21.59 mm |
| December | -10.2 °C | -0.9 °C | 24.64 mm |
| Annual | -0.4 °C | 13.9 °C | 309.36 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |