Denver, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37 °F (low) to 57.1 °F (high). Annual precipitation averages 37.7 Inches. Denver 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 | 8.7 °F | 25.9 °F | 1.06 in. |
| February | 12.8 °F | 30.1 °F | 1.13 in. |
| March | 24.5 °F | 43.5 °F | 1.99 in. |
| April | 36.1 °F | 58.3 °F | 3.95 in. |
| May | 48.6 °F | 70.2 °F | 4.94 in. |
| June | 59.4 °F | 79.9 °F | 5.86 in. |
| July | 62.4 °F | 82.8 °F | 4.62 in. |
| August | 59.7 °F | 80.9 °F | 4.16 in. |
| September | 50.9 °F | 74.9 °F | 3.61 in. |
| October | 38.6 °F | 61.4 °F | 2.85 in. |
| November | 26.3 °F | 45.1 °F | 1.93 in. |
| December | 15.5 °F | 31.7 °F | 1.56 in. |
| Annual | 37 °F | 57.1 °F | 37.66 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |