Alton, Kansas has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.4 °C (low) to 19.3 °C (high). Annual precipitation averages 678.9 Millimeters. Alton 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 | -8.9 °C | 4.7 °C | 15.49 mm |
| February | -7.3 °C | 7.1 °C | 18.8 mm |
| March | -2.3 °C | 13.4 °C | 36.83 mm |
| April | 3.2 °C | 19 °C | 57.66 mm |
| May | 9.6 °C | 24.2 °C | 101.6 mm |
| June | 15.9 °C | 30.6 °C | 94.49 mm |
| July | 18.8 °C | 33.7 °C | 112.01 mm |
| August | 17.5 °C | 32.1 °C | 90.68 mm |
| September | 12.2 °C | 27.8 °C | 53.09 mm |
| October | 4.3 °C | 20.8 °C | 45.21 mm |
| November | -2.6 °C | 12.6 °C | 28.7 mm |
| December | -7.6 °C | 5.9 °C | 24.38 mm |
| Annual | 4.4 °C | 19.3 °C | 678.94 mm |
| 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 : -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 |