Tiffin, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.5 °F (low) to 59.7 °F (high). Annual precipitation averages 37.6 Inches. Tiffin is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.8 °F | 29.6 °F | 1.19 in. |
| February | 16.5 °F | 34.2 °F | 1.43 in. |
| March | 27.4 °F | 47.3 °F | 2.24 in. |
| April | 38.6 °F | 61.3 °F | 3.77 in. |
| May | 50.6 °F | 72.1 °F | 4.69 in. |
| June | 60.7 °F | 81.2 °F | 5.3 in. |
| July | 64.2 °F | 84.6 °F | 4.38 in. |
| August | 61.6 °F | 82.7 °F | 4.25 in. |
| September | 52.9 °F | 76.8 °F | 3.53 in. |
| October | 40.9 °F | 63.6 °F | 2.93 in. |
| November | 29.0 °F | 48.2 °F | 2.2 in. |
| December | 18.7 °F | 34.9 °F | 1.66 in. |
| Annual | 39.5 °F | 59.7 °F | 37.57 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |