Oostburg, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.3 °C (low) to 12.4 °C (high). Annual precipitation averages 840.2 Millimeters. Oostburg is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.3 °C | -2.4 °C | 41.15 mm |
| February | -8.9 °C | -0.7 °C | 35.81 mm |
| March | -4 °C | 4.7 °C | 51.05 mm |
| April | 1.5 °C | 10.9 °C | 93.22 mm |
| May | 7.1 °C | 17.3 °C | 98.81 mm |
| June | 12.7 °C | 23.1 °C | 95.5 mm |
| July | 16.1 °C | 26.4 °C | 90.42 mm |
| August | 15.8 °C | 25.4 °C | 88.65 mm |
| September | 11.7 °C | 21.7 °C | 66.04 mm |
| October | 5.3 °C | 14.6 °C | 73.91 mm |
| November | -0.9 °C | 7.2 °C | 56.13 mm |
| December | -6.8 °C | 0.8 °C | 49.53 mm |
| Annual | 3.3 °C | 12.4 °C | 840.22 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |