Flat, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 13.2 °C (low) to 25.8 °C (high). Annual precipitation averages 879.4 Millimeters. Flat is located in USDA Plant Hardiness Zone 8b. 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 | 2.6 °C | 15.4 °C | 56.9 mm |
| February | 4.7 °C | 17.5 °C | 60.45 mm |
| March | 8.6 °C | 21.3 °C | 78.74 mm |
| April | 12.8 °C | 25.6 °C | 69.34 mm |
| May | 17.7 °C | 29.2 °C | 112.01 mm |
| June | 21.6 °C | 33.1 °C | 89.41 mm |
| July | 22.9 °C | 35.3 °C | 47.75 mm |
| August | 22.8 °C | 35.7 °C | 61.47 mm |
| September | 19.4 °C | 32.2 °C | 69.85 mm |
| October | 13.7 °C | 26.9 °C | 102.36 mm |
| November | 7.9 °C | 20.7 °C | 67.06 mm |
| December | 3.7 °C | 16.2 °C | 64.01 mm |
| Annual | 13.2 °C | 25.8 °C | 879.35 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 8b : -9.4°C to -6.7°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 |