Westerville, Nebraska has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 2.3 °C (low) to 16.4 °C (high). Annual precipitation averages 641.6 Millimeters. Westerville is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.9 °C | 2.3 °C | 12.7 mm |
| February | -9.3 °C | 4.2 °C | 16.76 mm |
| March | -4.2 °C | 10.5 °C | 35.05 mm |
| April | 1.2 °C | 15.9 °C | 73.41 mm |
| May | 7.6 °C | 21.4 °C | 102.62 mm |
| June | 13.7 °C | 27.3 °C | 96.27 mm |
| July | 16.6 °C | 30.3 °C | 81.53 mm |
| August | 15.2 °C | 29.2 °C | 77.22 mm |
| September | 9.5 °C | 25.1 °C | 55.12 mm |
| October | 2 °C | 17.8 °C | 49.02 mm |
| November | -4.8 °C | 9.9 °C | 24.13 mm |
| December | -9.6 °C | 3.4 °C | 17.78 mm |
| Annual | 2.3 °C | 16.4 °C | 641.61 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |