Niangua, Missouri has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.6 °C (low) to 19.1 °C (high). Annual precipitation averages 1166.9 Millimeters. Niangua is located in USDA Plant Hardiness Zone 6b. 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 °C | 5.7 °C | 66.04 mm |
| February | -2.9 °C | 8.4 °C | 62.48 mm |
| March | 1.7 °C | 13.7 °C | 96.52 mm |
| April | 7.1 °C | 19.5 °C | 117.6 mm |
| May | 12.4 °C | 23.9 °C | 141.48 mm |
| June | 17.3 °C | 28.4 °C | 114.3 mm |
| July | 19.7 °C | 31 °C | 113.79 mm |
| August | 18.8 °C | 30.7 °C | 90.93 mm |
| September | 14.4 °C | 26.7 °C | 108.46 mm |
| October | 8 °C | 20.4 °C | 90.17 mm |
| November | 2.1 °C | 13.4 °C | 95.25 mm |
| December | -2.7 °C | 7.4 °C | 69.85 mm |
| Annual | 7.6 °C | 19.1 °C | 1166.87 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 6b : -20.6°C to -17.8°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 |