Plymouth, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36.7 °F (low) to 54.6 °F (high). Annual precipitation averages 33.1 Inches. Plymouth is located in USDA Plant Hardiness Zone 5a. 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 | 6.8 °F | 22.9 °F | 0.94 in. |
| February | 10.1 °F | 27.7 °F | 0.9 in. |
| March | 22.2 °F | 40.4 °F | 1.66 in. |
| April | 35.7 °F | 55.2 °F | 3.01 in. |
| May | 48.5 °F | 68.2 °F | 4.34 in. |
| June | 58.9 °F | 77.8 °F | 4.74 in. |
| July | 63.6 °F | 82.4 °F | 4.24 in. |
| August | 61.2 °F | 80.0 °F | 4.25 in. |
| September | 52.9 °F | 72.4 °F | 3.46 in. |
| October | 39.7 °F | 57.9 °F | 2.55 in. |
| November | 26.7 °F | 42.1 °F | 1.65 in. |
| December | 13.7 °F | 28.1 °F | 1.33 in. |
| Annual | 36.7 °F | 54.6 °F | 33.07 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |