Idaho City, Idaho has a Humid Continental Climate - Dry Warm Summer climate (Köppen classification: Dsa). Average annual temperatures range from -0.2 °C (low) to 15.9 °C (high). Annual precipitation averages 524.3 Millimeters. Idaho City is located in USDA Plant Hardiness Zone 6a. 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 | -8.5 °C | 2.1 °C | 78.49 mm |
| February | -7.1 °C | 5.6 °C | 50.29 mm |
| March | -3.9 °C | 9.9 °C | 51.82 mm |
| April | -1.2 °C | 14.5 °C | 41.91 mm |
| May | 2.8 °C | 19.9 °C | 50.04 mm |
| June | 6 °C | 24.8 °C | 27.43 mm |
| July | 9.5 °C | 31.4 °C | 8.13 mm |
| August | 8.7 °C | 30.9 °C | 10.92 mm |
| September | 4.6 °C | 25.3 °C | 17.27 mm |
| October | -0.7 °C | 16.9 °C | 38.35 mm |
| November | -4.7 °C | 7.3 °C | 59.44 mm |
| December | -8.3 °C | 1.8 °C | 90.17 mm |
| Annual | -0.2 °C | 15.9 °C | 524.26 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 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dsa - Humid Continental Climate - Dry Warm Summer |