Alden, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.7 °C (low) to 14 °C (high). Annual precipitation averages 924.6 Millimeters. Alden 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 | -12.8 °C | -3.3 °C | 21.59 mm |
| February | -10.6 °C | -0.7 °C | 25.15 mm |
| March | -4.1 °C | 6.5 °C | 52.07 mm |
| April | 2.1 °C | 14.6 °C | 95.25 mm |
| May | 9.2 °C | 21.3 °C | 129.54 mm |
| June | 15.1 °C | 26.7 °C | 150.62 mm |
| July | 16.8 °C | 28.2 °C | 112.78 mm |
| August | 15.3 °C | 27.1 °C | 108.97 mm |
| September | 10.3 °C | 23.8 °C | 84.33 mm |
| October | 3.5 °C | 16.6 °C | 64.77 mm |
| November | -3.3 °C | 7.3 °C | 44.7 mm |
| December | -9.3 °C | -0.1 °C | 34.8 mm |
| Annual | 2.7 °C | 14 °C | 924.57 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 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 |