Brilliant, Alabama has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.5 °C (low) to 22.4 °C (high). Annual precipitation averages 1573.5 Millimeters. Brilliant is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.2 °C | 10.8 °C | 145.03 mm |
| February | 0.6 °C | 13.4 °C | 148.59 mm |
| March | 4.3 °C | 18.2 °C | 140.46 mm |
| April | 8.7 °C | 22.8 °C | 149.86 mm |
| May | 13.9 °C | 26.8 °C | 139.95 mm |
| June | 18.4 °C | 30.4 °C | 128.02 mm |
| July | 20.3 °C | 32 °C | 128.78 mm |
| August | 19.8 °C | 32 °C | 112.78 mm |
| September | 16.2 °C | 29.3 °C | 103.89 mm |
| October | 9.4 °C | 23.7 °C | 98.81 mm |
| November | 3.3 °C | 17.2 °C | 118.36 mm |
| December | 0.6 °C | 12.3 °C | 159 mm |
| Annual | 9.5 °C | 22.4 °C | 1573.53 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |