Gridley, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41 °F (low) to 61.4 °F (high). Annual precipitation averages 37.2 Inches. Gridley is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 16.0 °F | 32.3 °F | 2.13 in. |
| February | 19.4 °F | 37.1 °F | 1.83 in. |
| March | 28.9 °F | 49.2 °F | 2.59 in. |
| April | 39.6 °F | 62.6 °F | 3.66 in. |
| May | 51.4 °F | 73.7 °F | 4.45 in. |
| June | 61.0 °F | 82.3 °F | 4.04 in. |
| July | 64.1 °F | 85.2 °F | 3.84 in. |
| August | 61.9 °F | 83.4 °F | 3.43 in. |
| September | 53.9 °F | 78.3 °F | 3.33 in. |
| October | 42.6 °F | 65.5 °F | 3.28 in. |
| November | 31.5 °F | 50.1 °F | 2.63 in. |
| December | 21.8 °F | 37.5 °F | 2.03 in. |
| Annual | 41 °F | 61.4 °F | 37.24 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 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 |