Seneca, Missouri has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.4 °C (low) to 20.8 °C (high). Annual precipitation averages 1197.1 Millimeters. Seneca 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 | -4 °C | 7.8 °C | 54.61 mm |
| February | -2.2 °C | 10.3 °C | 56.9 mm |
| March | 2.7 °C | 15.6 °C | 91.19 mm |
| April | 7.8 °C | 20.9 °C | 123.44 mm |
| May | 13.4 °C | 25.1 °C | 174.75 mm |
| June | 18.4 °C | 29.9 °C | 134.11 mm |
| July | 20.7 °C | 32.7 °C | 98.3 mm |
| August | 19.7 °C | 32.4 °C | 87.88 mm |
| September | 15.2 °C | 28.2 °C | 124.21 mm |
| October | 8.5 °C | 21.9 °C | 100.08 mm |
| November | 2.6 °C | 15.3 °C | 85.34 mm |
| December | -2.2 °C | 9.3 °C | 66.29 mm |
| Annual | 8.4 °C | 20.8 °C | 1197.1 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 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 |