Brimfield, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40 °F (low) to 60.8 °F (high). Annual precipitation averages 38.3 Inches. Brimfield is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 14.4 °F | 31.5 °F | 1.96 in. |
| February | 17.9 °F | 36.1 °F | 1.97 in. |
| March | 28.0 °F | 48.9 °F | 2.48 in. |
| April | 38.7 °F | 62.2 °F | 3.71 in. |
| May | 50.7 °F | 73.0 °F | 4.96 in. |
| June | 60.5 °F | 81.7 °F | 4.52 in. |
| July | 63.7 °F | 84.6 °F | 3.98 in. |
| August | 61.4 °F | 83.0 °F | 3.56 in. |
| September | 53.0 °F | 77.3 °F | 3.62 in. |
| October | 41.3 °F | 64.7 °F | 2.96 in. |
| November | 30.0 °F | 49.6 °F | 2.54 in. |
| December | 20.3 °F | 36.9 °F | 2.0 in. |
| Annual | 40 °F | 60.8 °F | 38.26 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |