Rock Valley, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 36.1 °F (low) to 58 °F (high). Annual precipitation averages 28.6 Inches. Rock Valley 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 | 8.1 °F | 26.6 °F | 0.59 in. |
| February | 12.5 °F | 31.6 °F | 0.78 in. |
| March | 23.8 °F | 44.4 °F | 1.51 in. |
| April | 35.0 °F | 59.1 °F | 2.93 in. |
| May | 47.6 °F | 71.3 °F | 3.95 in. |
| June | 58.9 °F | 81.4 °F | 4.69 in. |
| July | 62.2 °F | 84.7 °F | 3.26 in. |
| August | 59.6 °F | 82.4 °F | 3.32 in. |
| September | 50.1 °F | 76.0 °F | 2.91 in. |
| October | 37.3 °F | 62.3 °F | 2.48 in. |
| November | 24.3 °F | 45.2 °F | 1.34 in. |
| December | 13.6 °F | 31.3 °F | 0.88 in. |
| Annual | 36.1 °F | 58 °F | 28.64 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 | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |