Bellflower, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.1 °F (low) to 61.4 °F (high). Annual precipitation averages 39.2 Inches. Bellflower is located in USDA Plant Hardiness Zone 6a. 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 | 16.6 °F | 32.9 °F | 2.25 in. |
| February | 19.9 °F | 37.3 °F | 1.95 in. |
| March | 29.0 °F | 49.1 °F | 2.66 in. |
| April | 39.7 °F | 62.5 °F | 3.88 in. |
| May | 51.7 °F | 73.4 °F | 4.46 in. |
| June | 61.1 °F | 81.9 °F | 4.51 in. |
| July | 63.9 °F | 84.5 °F | 4.14 in. |
| August | 61.5 °F | 83.0 °F | 3.53 in. |
| September | 53.9 °F | 78.2 °F | 3.3 in. |
| October | 42.3 °F | 65.4 °F | 3.33 in. |
| November | 31.5 °F | 50.4 °F | 2.89 in. |
| December | 22.2 °F | 37.7 °F | 2.3 in. |
| Annual | 41.1 °F | 61.4 °F | 39.2 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°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 |