Grey Forest, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 13.3 °C (low) to 25.9 °C (high). Annual precipitation averages 956.3 Millimeters. Grey Forest 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. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.4 °C | 16.5 °C | 53.85 mm |
| February | 5.6 °C | 18.9 °C | 51.56 mm |
| March | 9.2 °C | 22.3 °C | 69.85 mm |
| April | 12.8 °C | 25.9 °C | 65.02 mm |
| May | 17.6 °C | 29.3 °C | 118.36 mm |
| June | 21.1 °C | 32.6 °C | 100.84 mm |
| July | 22 °C | 34.1 °C | 71.63 mm |
| August | 21.9 °C | 34.7 °C | 76.45 mm |
| September | 19.2 °C | 31.5 °C | 107.19 mm |
| October | 14 °C | 27 °C | 107.95 mm |
| November | 8.4 °C | 21.3 °C | 75.44 mm |
| December | 4.3 °C | 17.2 °C | 58.17 mm |
| Annual | 13.3 °C | 25.9 °C | 956.31 mm |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| 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 |