Keystone, Nebraska has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 2.5 °C (low) to 17.5 °C (high). Annual precipitation averages 490.7 Millimeters. Keystone is located in USDA Plant Hardiness Zone 6a. 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 | -9.1 °C | 4.1 °C | 8.38 mm |
| February | -7.9 °C | 5.6 °C | 13.21 mm |
| March | -3.9 °C | 11.8 °C | 25.15 mm |
| April | 0.9 °C | 16.3 °C | 54.86 mm |
| May | 7.1 °C | 21.7 °C | 87.63 mm |
| June | 13.1 °C | 28.3 °C | 83.06 mm |
| July | 16.1 °C | 31.7 °C | 72.39 mm |
| August | 15 °C | 30.5 °C | 54.1 mm |
| September | 9.8 °C | 26.1 °C | 37.85 mm |
| October | 2.2 °C | 18.3 °C | 32.77 mm |
| November | -4.2 °C | 10.7 °C | 12.7 mm |
| December | -8.8 °C | 4.6 °C | 8.64 mm |
| Annual | 2.5 °C | 17.5 °C | 490.74 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 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 | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |