Plymouth, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.6 °C (low) to 12.5 °C (high). Annual precipitation averages 840 Millimeters. 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 | -14 °C | -5.1 °C | 23.88 mm |
| February | -12.2 °C | -2.4 °C | 22.86 mm |
| March | -5.4 °C | 4.7 °C | 42.16 mm |
| April | 2.1 °C | 12.9 °C | 76.45 mm |
| May | 9.2 °C | 20.1 °C | 110.24 mm |
| June | 14.9 °C | 25.4 °C | 120.4 mm |
| July | 17.6 °C | 28 °C | 107.7 mm |
| August | 16.2 °C | 26.7 °C | 107.95 mm |
| September | 11.6 °C | 22.4 °C | 87.88 mm |
| October | 4.3 °C | 14.4 °C | 64.77 mm |
| November | -2.9 °C | 5.6 °C | 41.91 mm |
| December | -10.2 °C | -2.2 °C | 33.78 mm |
| Annual | 2.6 °C | 12.5 °C | 839.98 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |