Costilla, New Mexico has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.8 °C (low) to 15.2 °C (high). Annual precipitation averages 319.8 Millimeters. Costilla 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 | -14.9 °C | 2.3 °C | 14.48 mm |
| February | -11.2 °C | 4.9 °C | 12.95 mm |
| March | -6.7 °C | 10.3 °C | 22.1 mm |
| April | -3.3 °C | 14.8 °C | 24.38 mm |
| May | 1.3 °C | 19.7 °C | 28.7 mm |
| June | 5.6 °C | 25.6 °C | 18.8 mm |
| July | 8.9 °C | 27.2 °C | 46.23 mm |
| August | 8 °C | 26.1 °C | 46.99 mm |
| September | 3.9 °C | 22.9 °C | 35.81 mm |
| October | -2.3 °C | 16.9 °C | 28.19 mm |
| November | -8.6 °C | 9.3 °C | 20.32 mm |
| December | -14.1 °C | 2.7 °C | 20.83 mm |
| Annual | -2.8 °C | 15.2 °C | 319.78 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 | Dfb - Humid Continental Mild Summer, Wet All Year |