McGregor, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.9 °C (low) to 14 °C (high). Annual precipitation averages 957.3 Millimeters. McGregor 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 | -12.5 °C | -2.8 °C | 30.99 mm |
| February | -10.5 °C | -0.3 °C | 31.24 mm |
| March | -4.1 °C | 6.7 °C | 51.05 mm |
| April | 2.3 °C | 14.4 °C | 101.09 mm |
| May | 8.7 °C | 20.9 °C | 119.89 mm |
| June | 14.5 °C | 26.2 °C | 147.83 mm |
| July | 16.7 °C | 28.2 °C | 108.46 mm |
| August | 15.4 °C | 27.2 °C | 104.65 mm |
| September | 10.8 °C | 23.4 °C | 99.57 mm |
| October | 4.1 °C | 16.2 °C | 70.61 mm |
| November | -2.6 °C | 7.3 °C | 52.58 mm |
| December | -8.5 °C | 0.3 °C | 39.37 mm |
| Annual | 2.9 °C | 14 °C | 957.33 mm |
| 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 : -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 |