Dennis, Kansas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8 °C (low) to 19.8 °C (high). Annual precipitation averages 1102.4 Millimeters. Dennis is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.2 °C | 6.3 °C | 38.1 mm |
| February | -3.1 °C | 9 °C | 43.69 mm |
| March | 1.9 °C | 14.5 °C | 72.14 mm |
| April | 7.5 °C | 19.7 °C | 115.57 mm |
| May | 13.4 °C | 24.3 °C | 168.4 mm |
| June | 18.7 °C | 29.4 °C | 139.7 mm |
| July | 20.9 °C | 32.2 °C | 104.39 mm |
| August | 19.8 °C | 31.9 °C | 98.81 mm |
| September | 15.1 °C | 27.5 °C | 108.2 mm |
| October | 8.3 °C | 21.2 °C | 97.28 mm |
| November | 1.9 °C | 14.1 °C | 66.04 mm |
| December | -3.1 °C | 8 °C | 50.04 mm |
| Annual | 8 °C | 19.8 °C | 1102.36 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |