Holy Cross, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.5 °C (low) to 12.9 °C (high). Annual precipitation averages 990.8 Millimeters. Holy Cross is located in USDA Plant Hardiness Zone 5a. 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 | -12.7 °C | -3.9 °C | 32 mm |
| February | -10.7 °C | -1.4 °C | 34.54 mm |
| March | -4.3 °C | 5.7 °C | 52.83 mm |
| April | 2.1 °C | 13.5 °C | 100.08 mm |
| May | 8.6 °C | 19.8 °C | 118.11 mm |
| June | 14.2 °C | 25.1 °C | 150.37 mm |
| July | 16.2 °C | 26.9 °C | 124.46 mm |
| August | 15.1 °C | 25.9 °C | 105.66 mm |
| September | 10.3 °C | 22.2 °C | 98.55 mm |
| October | 3.6 °C | 15.1 °C | 75.18 mm |
| November | -3 °C | 6.4 °C | 56.64 mm |
| December | -9 °C | -0.7 °C | 42.42 mm |
| Annual | 2.5 °C | 12.9 °C | 990.84 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 5a : -28.9°C to -26.1°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 |