Lyman, Nebraska has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 1 °C (low) to 17.5 °C (high). Annual precipitation averages 393.2 Millimeters. Lyman is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.6 °C | 4.8 °C | 6.35 mm |
| February | -8.7 °C | 6.2 °C | 12.95 mm |
| March | -4.4 °C | 11.6 °C | 21.34 mm |
| April | -0.3 °C | 15.8 °C | 50.55 mm |
| May | 5.4 °C | 21.2 °C | 73.15 mm |
| June | 10.8 °C | 27.9 °C | 62.48 mm |
| July | 14.3 °C | 31.9 °C | 41.91 mm |
| August | 12.8 °C | 30.9 °C | 26.42 mm |
| September | 7.2 °C | 26.1 °C | 39.37 mm |
| October | -0.1 °C | 17.9 °C | 37.08 mm |
| November | -5.9 °C | 10.5 °C | 11.68 mm |
| December | -10 °C | 5 °C | 9.91 mm |
| Annual | 1 °C | 17.5 °C | 393.19 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |