Riley, Kansas has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.4 °C (low) to 18.7 °C (high). Annual precipitation averages 844.8 Millimeters. Riley is located in USDA Plant Hardiness Zone 6b. 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 | -7.5 °C | 3.9 °C | 18.29 mm |
| February | -5.5 °C | 6.6 °C | 27.43 mm |
| March | 0.2 °C | 13 °C | 50.55 mm |
| April | 5.4 °C | 18.7 °C | 80.01 mm |
| May | 11.8 °C | 23.7 °C | 126.75 mm |
| June | 17.6 °C | 29.7 °C | 122.17 mm |
| July | 19.8 °C | 32.2 °C | 111.51 mm |
| August | 18.9 °C | 31.1 °C | 102.62 mm |
| September | 13.9 °C | 26.9 °C | 75.95 mm |
| October | 7.1 °C | 20.1 °C | 62.48 mm |
| November | 0.1 °C | 12.4 °C | 38.35 mm |
| December | -5 °C | 5.8 °C | 28.7 mm |
| Annual | 6.4 °C | 18.7 °C | 844.81 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 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |