Richmond, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.1 °F (low) to 57.5 °F (high). Annual precipitation averages 37.5 Inches. Richmond is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 13.4 °F | 29.0 °F | 1.78 in. |
| February | 16.1 °F | 32.9 °F | 1.85 in. |
| March | 25.4 °F | 44.2 °F | 2.17 in. |
| April | 35.7 °F | 57.1 °F | 3.78 in. |
| May | 46.8 °F | 68.6 °F | 4.41 in. |
| June | 56.9 °F | 78.4 °F | 4.84 in. |
| July | 61.3 °F | 82.4 °F | 3.74 in. |
| August | 59.6 °F | 80.8 °F | 3.82 in. |
| September | 51.8 °F | 74.2 °F | 3.61 in. |
| October | 40.5 °F | 60.9 °F | 3.05 in. |
| November | 29.8 °F | 46.7 °F | 2.41 in. |
| December | 19.5 °F | 34.2 °F | 1.99 in. |
| Annual | 38.1 °F | 57.5 °F | 37.45 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |