Thayer, Missouri has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.5 °C (low) to 20.8 °C (high). Annual precipitation averages 1229.6 Millimeters. Thayer is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.4 °C | 7.9 °C | 79.76 mm |
| February | -2.4 °C | 10.6 °C | 87.12 mm |
| March | 2 °C | 15.7 °C | 116.59 mm |
| April | 7.1 °C | 21.6 °C | 136.65 mm |
| May | 12.5 °C | 25.4 °C | 136.14 mm |
| June | 17.3 °C | 29.9 °C | 89.92 mm |
| July | 19.4 °C | 32.1 °C | 96.77 mm |
| August | 18.6 °C | 31.8 °C | 91.19 mm |
| September | 13.9 °C | 27.9 °C | 93.98 mm |
| October | 7.2 °C | 22.1 °C | 95.76 mm |
| November | 1.7 °C | 15.1 °C | 116.84 mm |
| December | -2.4 °C | 9.3 °C | 88.9 mm |
| Annual | 7.5 °C | 20.8 °C | 1229.62 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |