Elroy, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.6 °C (low) to 12.9 °C (high). Annual precipitation averages 936.5 Millimeters. Elroy is located in USDA Plant Hardiness Zone 4b. 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 | -13.6 °C | -3.7 °C | 33.27 mm |
| February | -11.9 °C | -1.1 °C | 30.48 mm |
| March | -5.7 °C | 5.6 °C | 49.02 mm |
| April | 0.8 °C | 13.2 °C | 99.06 mm |
| May | 7.5 °C | 19.9 °C | 115.57 mm |
| June | 13.1 °C | 25.1 °C | 136.91 mm |
| July | 15.3 °C | 27.3 °C | 106.43 mm |
| August | 14.1 °C | 26.1 °C | 111.76 mm |
| September | 9.3 °C | 22.2 °C | 93.98 mm |
| October | 2.9 °C | 14.8 °C | 70.36 mm |
| November | -3.4 °C | 6.4 °C | 50.04 mm |
| December | -9.6 °C | -0.7 °C | 39.62 mm |
| Annual | 1.6 °C | 12.9 °C | 936.5 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 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |