Brilliant, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.4 °F (low) to 62.6 °F (high). Annual precipitation averages 42.2 Inches. Brilliant is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 21.6 °F | 37.8 °F | 3.34 in. |
| February | 23.2 °F | 40.8 °F | 2.57 in. |
| March | 29.9 °F | 50.3 °F | 3.33 in. |
| April | 40.0 °F | 63.5 °F | 3.78 in. |
| May | 50.1 °F | 73.3 °F | 4.18 in. |
| June | 58.9 °F | 80.9 °F | 4.38 in. |
| July | 63.3 °F | 84.1 °F | 4.19 in. |
| August | 61.9 °F | 83.0 °F | 3.63 in. |
| September | 55.0 °F | 77.2 °F | 3.51 in. |
| October | 43.6 °F | 65.3 °F | 3.17 in. |
| November | 33.9 °F | 52.7 °F | 2.97 in. |
| December | 27.2 °F | 42.1 °F | 3.12 in. |
| Annual | 42.4 °F | 62.6 °F | 42.17 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |