Van Alstyne, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11.9 °C (low) to 23.5 °C (high). Annual precipitation averages 1075.4 Millimeters. Van Alstyne is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.4 °C | 11.9 °C | 62.48 mm |
| February | 2.4 °C | 14.4 °C | 74.93 mm |
| March | 6.5 °C | 18.7 °C | 96.01 mm |
| April | 10.8 °C | 22.9 °C | 96.27 mm |
| May | 16.1 °C | 27 °C | 133.86 mm |
| June | 20.9 °C | 31.6 °C | 100.33 mm |
| July | 23.2 °C | 34.4 °C | 67.06 mm |
| August | 22.9 °C | 34.6 °C | 64.01 mm |
| September | 18.8 °C | 30.6 °C | 85.85 mm |
| October | 12.6 °C | 24.8 °C | 119.63 mm |
| November | 6.6 °C | 18.2 °C | 86.61 mm |
| December | 1.8 °C | 13.1 °C | 88.39 mm |
| Annual | 11.9 °C | 23.5 °C | 1075.43 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |