Foster, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 45 °F (low) to 66.8 °F (high). Annual precipitation averages 43.6 Inches. Foster 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 | 21.0 °F | 41.1 °F | 1.57 in. |
| February | 24.7 °F | 46.2 °F | 1.94 in. |
| March | 34.0 °F | 56.7 °F | 2.9 in. |
| April | 43.9 °F | 66.9 °F | 4.58 in. |
| May | 54.7 °F | 75.8 °F | 6.12 in. |
| June | 64.4 °F | 84.6 °F | 5.55 in. |
| July | 68.6 °F | 89.5 °F | 4.47 in. |
| August | 66.3 °F | 88.5 °F | 3.84 in. |
| September | 57.4 °F | 81.1 °F | 4.38 in. |
| October | 45.5 °F | 69.7 °F | 3.47 in. |
| November | 34.4 °F | 56.1 °F | 2.74 in. |
| December | 25.2 °F | 44.8 °F | 2.07 in. |
| Annual | 45 °F | 66.8 °F | 43.63 in. |
| 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 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 |