Bertram, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39 °F (low) to 59.3 °F (high). Annual precipitation averages 38.7 Inches. Bertram 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.1 °F | 28.9 °F | 1.23 in. |
| February | 15.9 °F | 33.4 °F | 1.43 in. |
| March | 27.0 °F | 46.7 °F | 2.18 in. |
| April | 38.1 °F | 61.3 °F | 3.86 in. |
| May | 49.9 °F | 72.0 °F | 4.73 in. |
| June | 60.1 °F | 81.2 °F | 5.55 in. |
| July | 63.5 °F | 84.3 °F | 4.54 in. |
| August | 61.0 °F | 82.6 °F | 4.38 in. |
| September | 52.4 °F | 76.4 °F | 3.87 in. |
| October | 40.5 °F | 63.4 °F | 2.98 in. |
| November | 28.7 °F | 47.6 °F | 2.27 in. |
| December | 18.3 °F | 34.3 °F | 1.71 in. |
| Annual | 39 °F | 59.3 °F | 38.73 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| 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 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |