Swea City, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 36.2 °F (low) to 55.9 °F (high). Annual precipitation averages 32.4 Inches. Swea City 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 | 7.1 °F | 24.1 °F | 0.79 in. |
| February | 11.3 °F | 28.4 °F | 0.91 in. |
| March | 23.6 °F | 41.2 °F | 1.77 in. |
| April | 35.4 °F | 57.1 °F | 3.4 in. |
| May | 48.0 °F | 69.8 °F | 4.43 in. |
| June | 59.1 °F | 79.8 °F | 4.95 in. |
| July | 62.3 °F | 82.4 °F | 4.14 in. |
| August | 59.7 °F | 80.2 °F | 3.79 in. |
| September | 51.2 °F | 74.6 °F | 3.2 in. |
| October | 38.0 °F | 60.5 °F | 2.4 in. |
| November | 25.1 °F | 43.4 °F | 1.41 in. |
| December | 13.7 °F | 29.3 °F | 1.21 in. |
| Annual | 36.2 °F | 55.9 °F | 32.4 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 |