Herkimer, Kansas has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.2 °C (low) to 17.9 °C (high). Annual precipitation averages 822.7 Millimeters. Herkimer 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.7 °C | 2.7 °C | 19.05 mm |
| February | -6.7 °C | 5.3 °C | 26.67 mm |
| March | -1.1 °C | 12 °C | 50.8 mm |
| April | 4.4 °C | 17.8 °C | 78.49 mm |
| May | 10.9 °C | 23.4 °C | 120.9 mm |
| June | 16.7 °C | 28.9 °C | 116.84 mm |
| July | 19.1 °C | 31.5 °C | 111.25 mm |
| August | 17.7 °C | 30.7 °C | 88.65 mm |
| September | 12.4 °C | 26.6 °C | 82.55 mm |
| October | 5.4 °C | 19.7 °C | 61.21 mm |
| November | -1.2 °C | 11.4 °C | 36.32 mm |
| December | -6.5 °C | 4.7 °C | 29.97 mm |
| Annual | 5.2 °C | 17.9 °C | 822.7 mm |
| 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 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |