Worthington, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 36.8 °F (low) to 57.2 °F (high). Annual precipitation averages 38.9 Inches. Worthington is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 9.6 °F | 26.8 °F | 1.23 in. |
| February | 13.3 °F | 31.2 °F | 1.43 in. |
| March | 24.9 °F | 44.4 °F | 2.17 in. |
| April | 35.9 °F | 58.4 °F | 3.85 in. |
| May | 47.6 °F | 69.8 °F | 4.46 in. |
| June | 58.0 °F | 79.3 °F | 5.88 in. |
| July | 61.4 °F | 82.4 °F | 4.73 in. |
| August | 59.1 °F | 80.7 °F | 4.41 in. |
| September | 50.2 °F | 74.0 °F | 3.68 in. |
| October | 38.4 °F | 61.1 °F | 3.07 in. |
| November | 26.9 °F | 45.4 °F | 2.26 in. |
| December | 16.4 °F | 32.5 °F | 1.69 in. |
| Annual | 36.8 °F | 57.2 °F | 38.86 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |