Guymon, Oklahoma has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 5.3 °C (low) to 21.6 °C (high). Annual precipitation averages 442.2 Millimeters. Guymon is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.4 °C | 9.4 °C | 10.16 mm |
| February | -5.2 °C | 11.2 °C | 8.89 mm |
| March | -0.9 °C | 16.3 °C | 28.19 mm |
| April | 3.7 °C | 20.7 °C | 31.24 mm |
| May | 9.8 °C | 26.2 °C | 53.85 mm |
| June | 15.9 °C | 31.9 °C | 62.74 mm |
| July | 18.4 °C | 34.3 °C | 68.07 mm |
| August | 17.4 °C | 33.1 °C | 73.91 mm |
| September | 12.9 °C | 29.1 °C | 32.77 mm |
| October | 5.4 °C | 22.2 °C | 41.15 mm |
| November | -1.3 °C | 15.4 °C | 13.97 mm |
| December | -5.9 °C | 9.2 °C | 17.27 mm |
| Annual | 5.3 °C | 21.6 °C | 442.21 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |