Plymouth, Utah has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.7 °C (low) to 15.7 °C (high). Annual precipitation averages 381 Millimeters. Plymouth is located in USDA Plant Hardiness Zone 6a. 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 | -9.2 °C | 0.3 °C | 44.96 mm |
| February | -7.1 °C | 3.2 °C | 36.83 mm |
| March | -2.1 °C | 9.7 °C | 38.86 mm |
| April | 1.2 °C | 14.8 °C | 34.54 mm |
| May | 5.4 °C | 19.9 °C | 49.28 mm |
| June | 9.1 °C | 26.1 °C | 21.84 mm |
| July | 13.3 °C | 31.8 °C | 11.94 mm |
| August | 12.6 °C | 31.2 °C | 14.99 mm |
| September | 7.6 °C | 25.3 °C | 31.5 mm |
| October | 1.6 °C | 16.9 °C | 34.8 mm |
| November | -3.7 °C | 8.2 °C | 24.38 mm |
| December | -8.3 °C | 1.1 °C | 37.08 mm |
| Annual | 1.7 °C | 15.7 °C | 381 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |