San Luis, Colorado has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.9 °C (low) to 14.8 °C (high). Annual precipitation averages 267.7 Millimeters. San Luis is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -14.9 °C | 2.1 °C | 7.62 mm |
| February | -11.4 °C | 4.4 °C | 10.41 mm |
| March | -6.5 °C | 9.9 °C | 14.22 mm |
| April | -3.1 °C | 14.2 °C | 26.42 mm |
| May | 1.3 °C | 19.3 °C | 23.88 mm |
| June | 5.6 °C | 25.4 °C | 17.78 mm |
| July | 8.5 °C | 26.9 °C | 47.24 mm |
| August | 7.8 °C | 25.8 °C | 40.64 mm |
| September | 3.6 °C | 22.5 °C | 30.99 mm |
| October | -2.7 °C | 16.3 °C | 20.83 mm |
| November | -8.6 °C | 8.8 °C | 14.48 mm |
| December | -14 °C | 2.4 °C | 13.21 mm |
| Annual | -2.9 °C | 14.8 °C | 267.72 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |