Marietta, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.8 °F (low) to 54.6 °F (high). Annual precipitation averages 25.6 Inches. Marietta is located in USDA Plant Hardiness Zone 4b. 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 | 3.9 °F | 22.4 °F | 0.73 in. |
| February | 7.4 °F | 26.8 °F | 0.73 in. |
| March | 20.0 °F | 38.9 °F | 1.28 in. |
| April | 32.9 °F | 55.0 °F | 2.49 in. |
| May | 46.1 °F | 68.5 °F | 3.01 in. |
| June | 57.2 °F | 78.4 °F | 3.89 in. |
| July | 60.9 °F | 82.5 °F | 3.68 in. |
| August | 58.1 °F | 80.4 °F | 3.06 in. |
| September | 49.2 °F | 73.3 °F | 2.53 in. |
| October | 36.1 °F | 58.7 °F | 2.21 in. |
| November | 23.2 °F | 42.1 °F | 1.11 in. |
| December | 10.8 °F | 27.8 °F | 0.83 in. |
| Annual | 33.8 °F | 54.6 °F | 25.55 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 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |