Knox, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.8 °F (low) to 59.5 °F (high). Annual precipitation averages 40.9 Inches. Knox 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 | 16.0 °F | 31.8 °F | 2.58 in. |
| February | 18.8 °F | 35.8 °F | 2.29 in. |
| March | 27.4 °F | 47.0 °F | 2.52 in. |
| April | 37.8 °F | 59.5 °F | 3.67 in. |
| May | 49.6 °F | 70.7 °F | 4.34 in. |
| June | 59.4 °F | 79.9 °F | 4.48 in. |
| July | 61.8 °F | 82.7 °F | 4.54 in. |
| August | 59.9 °F | 81.0 °F | 4.29 in. |
| September | 52.0 °F | 75.8 °F | 3.42 in. |
| October | 41.1 °F | 63.5 °F | 3.42 in. |
| November | 31.3 °F | 49.0 °F | 2.91 in. |
| December | 22.2 °F | 37.2 °F | 2.42 in. |
| Annual | 39.8 °F | 59.5 °F | 40.88 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 | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |