Monroe, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.4 °C (low) to 15.5 °C (high). Annual precipitation averages 937.8 Millimeters. Monroe is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.7 °C | -0.9 °C | 25.65 mm |
| February | -8.6 °C | 1.6 °C | 33.78 mm |
| March | -2.5 °C | 8.8 °C | 52.32 mm |
| April | 3.8 °C | 16.3 °C | 100.08 mm |
| May | 10.6 °C | 21.8 °C | 127.51 mm |
| June | 16.3 °C | 27.3 °C | 135.13 mm |
| July | 18.3 °C | 29.3 °C | 110.24 mm |
| August | 16.9 °C | 28.4 °C | 109.98 mm |
| September | 12 °C | 24.9 °C | 91.44 mm |
| October | 5.2 °C | 17.6 °C | 66.8 mm |
| November | -1.5 °C | 9.2 °C | 48.77 mm |
| December | -7.4 °C | 1.9 °C | 36.07 mm |
| Annual | 4.4 °C | 15.5 °C | 937.77 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |