Marseilles, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.6 °F (low) to 60.1 °F (high). Annual precipitation averages 38.4 Inches. Marseilles 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 | 15.7 °F | 31.2 °F | 1.98 in. |
| February | 18.9 °F | 35.5 °F | 1.84 in. |
| March | 28.4 °F | 47.7 °F | 2.5 in. |
| April | 39.0 °F | 60.9 °F | 3.53 in. |
| May | 50.6 °F | 72.1 °F | 4.62 in. |
| June | 60.2 °F | 81.0 °F | 4.7 in. |
| July | 63.8 °F | 83.9 °F | 3.92 in. |
| August | 61.8 °F | 82.0 °F | 3.94 in. |
| September | 53.9 °F | 77.0 °F | 3.45 in. |
| October | 42.2 °F | 64.0 °F | 3.14 in. |
| November | 31.2 °F | 49.2 °F | 2.66 in. |
| December | 21.2 °F | 36.3 °F | 2.1 in. |
| Annual | 40.6 °F | 60.1 °F | 38.38 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 | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |