Riley, Kansas has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.5 °F (low) to 65.6 °F (high). Annual precipitation averages 33.3 Inches. 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 | 18.5 °F | 39.1 °F | 0.72 in. |
| February | 22.1 °F | 43.9 °F | 1.08 in. |
| March | 32.3 °F | 55.4 °F | 1.99 in. |
| April | 41.8 °F | 65.6 °F | 3.15 in. |
| May | 53.3 °F | 74.6 °F | 4.99 in. |
| June | 63.7 °F | 85.4 °F | 4.81 in. |
| July | 67.7 °F | 90.0 °F | 4.39 in. |
| August | 66.1 °F | 88.0 °F | 4.04 in. |
| September | 57.0 °F | 80.5 °F | 2.99 in. |
| October | 44.8 °F | 68.2 °F | 2.46 in. |
| November | 32.2 °F | 54.3 °F | 1.51 in. |
| December | 23.0 °F | 42.4 °F | 1.13 in. |
| Annual | 43.5 °F | 65.6 °F | 33.26 in. |
| 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 : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |