Ralston, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.6 °F (low) to 58.9 °F (high). Annual precipitation averages 34.3 Inches. Ralston 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 | 10.1 °F | 28.2 °F | 0.84 in. |
| February | 14.2 °F | 32.9 °F | 1.11 in. |
| March | 25.5 °F | 46.2 °F | 1.97 in. |
| April | 36.4 °F | 60.4 °F | 3.61 in. |
| May | 49.0 °F | 71.3 °F | 4.93 in. |
| June | 59.6 °F | 81.1 °F | 5.06 in. |
| July | 63.2 °F | 84.2 °F | 4.06 in. |
| August | 60.5 °F | 82.0 °F | 4.03 in. |
| September | 51.3 °F | 76.4 °F | 3.14 in. |
| October | 39.1 °F | 63.4 °F | 2.64 in. |
| November | 26.6 °F | 46.7 °F | 1.57 in. |
| December | 16.1 °F | 33.5 °F | 1.29 in. |
| Annual | 37.6 °F | 58.9 °F | 34.25 in. |
| 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 : -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 |