Fontanelle, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.1 °C (low) to 15.7 °C (high). Annual precipitation averages 902.7 Millimeters. Fontanelle 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 | -10.8 °C | -0.7 °C | 21.59 mm |
| February | -8.6 °C | 2.2 °C | 30.99 mm |
| March | -2.7 °C | 9.3 °C | 51.31 mm |
| April | 3.4 °C | 16.5 °C | 93.22 mm |
| May | 10.2 °C | 22.1 °C | 129.54 mm |
| June | 15.8 °C | 27.4 °C | 124.97 mm |
| July | 18 °C | 29.4 °C | 102.87 mm |
| August | 16.7 °C | 28.5 °C | 100.33 mm |
| September | 11.8 °C | 24.9 °C | 94.74 mm |
| October | 4.9 °C | 17.9 °C | 71.37 mm |
| November | -1.9 °C | 9.2 °C | 47.24 mm |
| December | -7.8 °C | 1.9 °C | 34.54 mm |
| Annual | 4.1 °C | 15.7 °C | 902.71 mm |
| 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 : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |