Galesburg, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.3 °F (low) to 60.3 °F (high). Annual precipitation averages 39 Inches. Galesburg 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 | 31.0 °F | 1.76 in. |
| February | 17.8 °F | 35.5 °F | 1.94 in. |
| March | 28.2 °F | 48.6 °F | 2.45 in. |
| April | 38.8 °F | 61.6 °F | 3.86 in. |
| May | 51.1 °F | 72.3 °F | 5.2 in. |
| June | 60.8 °F | 81.2 °F | 4.73 in. |
| July | 64.1 °F | 84.2 °F | 4.02 in. |
| August | 61.9 °F | 82.6 °F | 3.71 in. |
| September | 53.6 °F | 76.7 °F | 3.89 in. |
| October | 41.8 °F | 64.1 °F | 2.89 in. |
| November | 30.3 °F | 49.0 °F | 2.49 in. |
| December | 20.4 °F | 36.4 °F | 2.03 in. |
| Annual | 40.3 °F | 60.3 °F | 38.97 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |