Lamar, Arkansas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.7 °C (low) to 22.3 °C (high). Annual precipitation averages 1278.7 Millimeters. Lamar is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.8 °C | 9.8 °C | 88.65 mm |
| February | 0 °C | 12.6 °C | 78.49 mm |
| March | 4.2 °C | 17.3 °C | 117.09 mm |
| April | 8.9 °C | 22.5 °C | 129.29 mm |
| May | 14.4 °C | 26.6 °C | 136.91 mm |
| June | 19.2 °C | 30.9 °C | 103.89 mm |
| July | 21.1 °C | 33.5 °C | 97.79 mm |
| August | 20.6 °C | 33.6 °C | 91.19 mm |
| September | 16.3 °C | 29.7 °C | 94.74 mm |
| October | 9.6 °C | 23.4 °C | 106.17 mm |
| November | 3.8 °C | 16.5 °C | 126.75 mm |
| December | -0.3 °C | 10.9 °C | 107.7 mm |
| Annual | 9.7 °C | 22.3 °C | 1278.66 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |