Nampa, Idaho has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 4 °C (low) to 18.1 °C (high). Annual precipitation averages 277.6 Millimeters. Nampa is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.3 °C | 3.8 °C | 35.31 mm |
| February | -2.7 °C | 8.1 °C | 24.38 mm |
| March | 0.2 °C | 13.6 °C | 30.73 mm |
| April | 2.7 °C | 17.4 °C | 28.45 mm |
| May | 7.2 °C | 22.5 °C | 33.53 mm |
| June | 10.9 °C | 27.3 °C | 18.29 mm |
| July | 14.6 °C | 33.2 °C | 6.1 mm |
| August | 13.4 °C | 32.4 °C | 3.81 mm |
| September | 8.8 °C | 26.7 °C | 10.67 mm |
| October | 3.2 °C | 18.7 °C | 19.56 mm |
| November | -1.5 °C | 9.9 °C | 28.7 mm |
| December | -4.3 °C | 4.1 °C | 38.1 mm |
| Annual | 4 °C | 18.1 °C | 277.63 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |