McCook, Nebraska has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 3 °C (low) to 18.6 °C (high). Annual precipitation averages 548.7 Millimeters. McCook 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 | -9.7 °C | 4.9 °C | 7.37 mm |
| February | -8.3 °C | 6.6 °C | 14.22 mm |
| March | -3.6 °C | 12.9 °C | 26.42 mm |
| April | 1.7 °C | 17.9 °C | 56.39 mm |
| May | 8.1 °C | 23.2 °C | 78.49 mm |
| June | 14.2 °C | 29.4 °C | 84.58 mm |
| July | 17.3 °C | 32.6 °C | 85.09 mm |
| August | 15.9 °C | 31.2 °C | 79.25 mm |
| September | 10.4 °C | 27.2 °C | 41.15 mm |
| October | 2.7 °C | 19.8 °C | 41.66 mm |
| November | -4.3 °C | 11.9 °C | 20.07 mm |
| December | -8.9 °C | 5.4 °C | 13.97 mm |
| Annual | 3 °C | 18.6 °C | 548.66 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 | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |