Franklin, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.6 °C (low) to 16.6 °C (high). Annual precipitation averages 993.6 Millimeters. Franklin 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. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.8 °C | 0.6 °C | 39.37 mm |
| February | -6.8 °C | 3.2 °C | 47.75 mm |
| March | -1.1 °C | 10.1 °C | 64.26 mm |
| April | 5 °C | 17.3 °C | 95.5 mm |
| May | 11.6 °C | 22.9 °C | 130.3 mm |
| June | 16.9 °C | 28.2 °C | 126.24 mm |
| July | 19 °C | 30.2 °C | 106.93 mm |
| August | 17.8 °C | 29.3 °C | 97.28 mm |
| September | 13 °C | 25.7 °C | 96.27 mm |
| October | 6.6 °C | 18.5 °C | 77.98 mm |
| November | 0.1 °C | 10.2 °C | 62.74 mm |
| December | -5.6 °C | 3.3 °C | 49.02 mm |
| Annual | 5.6 °C | 16.6 °C | 993.64 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |