Dorchester, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 32 °F (low) to 52 °F (high). Annual precipitation averages 33.6 Inches. Dorchester is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.6 °F | 21.3 °F | 1.06 in. |
| February | 5.7 °F | 26.0 °F | 1.05 in. |
| March | 17.6 °F | 38.1 °F | 1.68 in. |
| April | 30.8 °F | 52.2 °F | 2.92 in. |
| May | 43.4 °F | 65.2 °F | 3.74 in. |
| June | 53.3 °F | 74.3 °F | 4.89 in. |
| July | 57.2 °F | 78.8 °F | 3.82 in. |
| August | 54.8 °F | 76.5 °F | 4.21 in. |
| September | 47.0 °F | 69.4 °F | 3.84 in. |
| October | 35.0 °F | 55.2 °F | 2.99 in. |
| November | 24.0 °F | 39.8 °F | 1.88 in. |
| December | 11.4 °F | 26.7 °F | 1.47 in. |
| Annual | 32 °F | 52 °F | 33.55 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |