Kirby, Arkansas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 49.1 °F (low) to 72.6 °F (high). Annual precipitation averages 58.1 Inches. Kirby 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 | 29.5 °F | 51.8 °F | 4.05 in. |
| February | 32.4 °F | 56.2 °F | 4.19 in. |
| March | 39.4 °F | 64.4 °F | 5.31 in. |
| April | 47.6 °F | 72.8 °F | 5.74 in. |
| May | 57.5 °F | 79.4 °F | 6.58 in. |
| June | 65.6 °F | 87.4 °F | 4.44 in. |
| July | 68.8 °F | 91.4 °F | 4.47 in. |
| August | 67.7 °F | 91.3 °F | 3.63 in. |
| September | 60.7 °F | 84.8 °F | 4.15 in. |
| October | 48.7 °F | 74.5 °F | 5.2 in. |
| November | 38.9 °F | 62.9 °F | 4.9 in. |
| December | 32.1 °F | 54.1 °F | 5.48 in. |
| Annual | 49.1 °F | 72.6 °F | 58.14 in. |
| 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 : 10°F to 15°F |
| Plant Hardiness Zone - 2012 | Zone 7b : 5°F to 10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |