Newton, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.3 °F (low) to 59.3 °F (high). Annual precipitation averages 36 Inches. Newton is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.0 °F | 29.2 °F | 0.94 in. |
| February | 16.0 °F | 33.9 °F | 1.19 in. |
| March | 26.9 °F | 47.0 °F | 2.01 in. |
| April | 38.1 °F | 60.7 °F | 3.72 in. |
| May | 50.5 °F | 71.4 °F | 4.89 in. |
| June | 60.9 °F | 81.0 °F | 5.13 in. |
| July | 64.4 °F | 84.4 °F | 4.2 in. |
| August | 61.8 °F | 82.4 °F | 4.33 in. |
| September | 53.0 °F | 76.5 °F | 3.6 in. |
| October | 40.8 °F | 63.2 °F | 2.64 in. |
| November | 28.6 °F | 47.7 °F | 1.99 in. |
| December | 18.1 °F | 34.7 °F | 1.31 in. |
| Annual | 39.3 °F | 59.3 °F | 35.95 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°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 |