Palmer, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.3 °F (low) to 63.6 °F (high). Annual precipitation averages 39.6 Inches. Palmer is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 19.5 °F | 35.5 °F | 2.28 in. |
| February | 23.0 °F | 40.6 °F | 1.98 in. |
| March | 32.1 °F | 51.9 °F | 2.77 in. |
| April | 42.5 °F | 64.7 °F | 4.22 in. |
| May | 53.7 °F | 74.9 °F | 4.69 in. |
| June | 62.7 °F | 83.4 °F | 4.46 in. |
| July | 65.6 °F | 86.4 °F | 3.75 in. |
| August | 63.4 °F | 85.2 °F | 3.28 in. |
| September | 55.3 °F | 80.0 °F | 3.25 in. |
| October | 43.9 °F | 67.6 °F | 3.28 in. |
| November | 33.5 °F | 52.4 °F | 3.24 in. |
| December | 24.8 °F | 40.5 °F | 2.35 in. |
| Annual | 43.3 °F | 63.6 °F | 39.55 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |