Anamosa, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.2 °C (low) to 14.6 °C (high). Annual precipitation averages 1003.3 Millimeters. Anamosa 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.7 °C | -2.3 °C | 33.27 mm |
| February | -9.7 °C | 0.2 °C | 38.35 mm |
| March | -3.4 °C | 7.6 °C | 59.94 mm |
| April | 2.7 °C | 15.4 °C | 99.82 mm |
| May | 9.1 °C | 21.6 °C | 120.65 mm |
| June | 14.8 °C | 26.7 °C | 139.95 mm |
| July | 16.8 °C | 28.4 °C | 125.98 mm |
| August | 15.4 °C | 27.4 °C | 111.76 mm |
| September | 10.6 °C | 23.9 °C | 93.22 mm |
| October | 4.1 °C | 16.8 °C | 77.98 mm |
| November | -2.4 °C | 8.2 °C | 58.67 mm |
| December | -8.1 °C | 0.8 °C | 43.69 mm |
| Annual | 3.2 °C | 14.6 °C | 1003.28 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| 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 |