Hazleton, Iowa has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.5 °C (low) to 13.8 °C (high). Annual precipitation averages 944.4 Millimeters. Hazleton 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 | -13.1 °C | -3.4 °C | 29.21 mm |
| February | -10.8 °C | -1.1 °C | 30.23 mm |
| March | -4.3 °C | 6.3 °C | 48.26 mm |
| April | 2.1 °C | 14.4 °C | 92.96 mm |
| May | 8.8 °C | 21 °C | 116.59 mm |
| June | 14.7 °C | 26.4 °C | 143.51 mm |
| July | 16.4 °C | 27.9 °C | 125.22 mm |
| August | 15 °C | 26.9 °C | 107.19 mm |
| September | 10.3 °C | 23.6 °C | 94.74 mm |
| October | 3.4 °C | 16.2 °C | 69.6 mm |
| November | -3.3 °C | 7.2 °C | 46.99 mm |
| December | -9.3 °C | -0.2 °C | 39.88 mm |
| Annual | 2.5 °C | 13.8 °C | 944.38 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |