Sam Rayburn, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12.8 °C (low) to 25.5 °C (high). Annual precipitation averages 1460 Millimeters. 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 | 3.1 °C | 15.6 °C | 135.13 mm |
| February | 4.9 °C | 17.7 °C | 113.79 mm |
| March | 8.6 °C | 21.5 °C | 124.21 mm |
| April | 12.2 °C | 25.3 °C | 118.62 mm |
| May | 16.9 °C | 29.3 °C | 114.55 mm |
| June | 20.7 °C | 32.4 °C | 132.84 mm |
| July | 21.7 °C | 34.1 °C | 101.35 mm |
| August | 21.6 °C | 34.4 °C | 114.55 mm |
| September | 18.8 °C | 31.6 °C | 101.6 mm |
| October | 12.8 °C | 26.8 °C | 130.05 mm |
| November | 7.6 °C | 20.8 °C | 129.54 mm |
| December | 4.1 °C | 16.4 °C | 143.76 mm |
| Annual | 12.8 °C | 25.5 °C | 1459.99 mm |
| 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 : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |