Fostoria, Iowa has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.6 °F (low) to 55.8 °F (high). Annual precipitation averages 30.5 Inches. Fostoria is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.8 °F | 24.2 °F | 0.7 in. |
| February | 10.8 °F | 28.5 °F | 0.8 in. |
| March | 22.6 °F | 41.3 °F | 1.58 in. |
| April | 34.6 °F | 56.8 °F | 3.34 in. |
| May | 47.3 °F | 69.1 °F | 4.3 in. |
| June | 58.3 °F | 79.3 °F | 4.65 in. |
| July | 62.0 °F | 83.0 °F | 3.67 in. |
| August | 59.3 °F | 80.4 °F | 3.64 in. |
| September | 50.7 °F | 74.3 °F | 3.17 in. |
| October | 37.5 °F | 60.2 °F | 2.34 in. |
| November | 24.4 °F | 43.6 °F | 1.4 in. |
| December | 12.8 °F | 29.4 °F | 0.93 in. |
| Annual | 35.6 °F | 55.8 °F | 30.52 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |