Sam Rayburn, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 55 °F (low) to 77.9 °F (high). Annual precipitation averages 57.5 Inches. Sam Rayburn is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 37.6 °F | 60.0 °F | 5.32 in. |
| February | 40.8 °F | 63.8 °F | 4.48 in. |
| March | 47.4 °F | 70.7 °F | 4.89 in. |
| April | 54.0 °F | 77.6 °F | 4.67 in. |
| May | 62.5 °F | 84.7 °F | 4.51 in. |
| June | 69.3 °F | 90.4 °F | 5.23 in. |
| July | 71.1 °F | 93.4 °F | 3.99 in. |
| August | 70.8 °F | 93.9 °F | 4.51 in. |
| September | 65.9 °F | 88.9 °F | 4.0 in. |
| October | 55.0 °F | 80.2 °F | 5.12 in. |
| November | 45.7 °F | 69.4 °F | 5.1 in. |
| December | 39.3 °F | 61.5 °F | 5.66 in. |
| Annual | 55 °F | 77.9 °F | 57.48 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |