Forsan, Texas has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 10.4 °C (low) to 25.1 °C (high). Annual precipitation averages 466.1 Millimeters. Forsan 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 | -0.6 °C | 14.2 °C | 19.3 mm |
| February | 1.4 °C | 16.7 °C | 22.35 mm |
| March | 5.3 °C | 21.2 °C | 30.48 mm |
| April | 9.6 °C | 25.9 °C | 34.8 mm |
| May | 15.3 °C | 30.6 °C | 54.36 mm |
| June | 20 °C | 34 °C | 57.15 mm |
| July | 21.3 °C | 34.7 °C | 35.05 mm |
| August | 20.9 °C | 34.2 °C | 53.34 mm |
| September | 17 °C | 30.1 °C | 68.83 mm |
| October | 10.9 °C | 25.8 °C | 38.35 mm |
| November | 4.2 °C | 19.1 °C | 33.02 mm |
| December | -0.1 °C | 14.5 °C | 19.05 mm |
| Annual | 10.4 °C | 25.1 °C | 466.08 mm |
| 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 : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |