Salem, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.9 °F (low) to 61.5 °F (high). Annual precipitation averages 38 Inches. Salem is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 15.8 °F | 32.4 °F | 1.47 in. |
| February | 19.4 °F | 37.0 °F | 1.76 in. |
| March | 29.8 °F | 49.7 °F | 2.45 in. |
| April | 40.8 °F | 62.9 °F | 3.72 in. |
| May | 52.6 °F | 73.1 °F | 5.18 in. |
| June | 62.3 °F | 82.3 °F | 4.97 in. |
| July | 65.9 °F | 85.9 °F | 4.14 in. |
| August | 63.7 °F | 84.4 °F | 3.68 in. |
| September | 55.0 °F | 77.9 °F | 3.64 in. |
| October | 43.4 °F | 65.0 °F | 2.94 in. |
| November | 31.9 °F | 50.1 °F | 2.26 in. |
| December | 21.7 °F | 37.5 °F | 1.76 in. |
| Annual | 41.9 °F | 61.5 °F | 37.97 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |