Fort Sumner, New Mexico has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 43.4 °F (low) to 74.8 °F (high). Annual precipitation averages 14.1 Inches. Fort Sumner is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 23.5 °F | 54.9 °F | 0.4 in. |
| February | 27.0 °F | 59.9 °F | 0.39 in. |
| March | 34.0 °F | 67.7 °F | 0.68 in. |
| April | 41.4 °F | 75.6 °F | 0.73 in. |
| May | 51.2 °F | 83.8 °F | 1.14 in. |
| June | 60.9 °F | 92.4 °F | 1.4 in. |
| July | 64.9 °F | 93.5 °F | 2.54 in. |
| August | 63.4 °F | 91.6 °F | 2.36 in. |
| September | 55.8 °F | 85.4 °F | 1.8 in. |
| October | 43.2 °F | 75.1 °F | 1.59 in. |
| November | 31.3 °F | 63.4 °F | 0.46 in. |
| December | 23.9 °F | 54.8 °F | 0.57 in. |
| Annual | 43.4 °F | 74.8 °F | 14.06 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |