Lamar, Colorado has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 3 °C (low) to 20.5 °C (high). Annual precipitation averages 386.8 Millimeters. Lamar is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.6 °C | 7.4 °C | 8.64 mm |
| February | -7.8 °C | 9.4 °C | 10.16 mm |
| March | -3.1 °C | 15.4 °C | 17.02 mm |
| April | 1.7 °C | 19.7 °C | 35.31 mm |
| May | 7.8 °C | 25 °C | 45.21 mm |
| June | 14.1 °C | 31.3 °C | 56.13 mm |
| July | 17.2 °C | 33.8 °C | 70.1 mm |
| August | 16.1 °C | 32.3 °C | 66.29 mm |
| September | 10.9 °C | 28.5 °C | 26.92 mm |
| October | 2.5 °C | 21.3 °C | 27.69 mm |
| November | -4.4 °C | 13.6 °C | 11.94 mm |
| December | -9.2 °C | 7.7 °C | 11.43 mm |
| Annual | 3 °C | 20.5 °C | 386.84 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |