Rupert, Idaho has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 1.5 °C (low) to 16.2 °C (high). Annual precipitation averages 262.4 Millimeters. Rupert 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 Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.3 °C | 2.2 °C | 30.73 mm |
| February | -5.7 °C | 5.2 °C | 17.78 mm |
| March | -2.2 °C | 10.9 °C | 25.4 mm |
| April | 0.4 °C | 15.1 °C | 26.42 mm |
| May | 4.8 °C | 20.4 °C | 36.32 mm |
| June | 8.5 °C | 25.3 °C | 18.8 mm |
| July | 12.1 °C | 31.1 °C | 6.1 mm |
| August | 11 °C | 30.6 °C | 10.16 mm |
| September | 6.4 °C | 25 °C | 14.99 mm |
| October | 1.1 °C | 17.3 °C | 21.59 mm |
| November | -3.8 °C | 8.8 °C | 22.35 mm |
| December | -7.3 °C | 2.4 °C | 31.75 mm |
| Annual | 1.5 °C | 16.2 °C | 262.39 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |