Johnson, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.6 °C (low) to 11.6 °C (high). Annual precipitation averages 650.5 Millimeters. Johnson is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -16.4 °C | -6.4 °C | 16 mm |
| February | -14.6 °C | -4.2 °C | 16 mm |
| March | -7.3 °C | 2.9 °C | 27.94 mm |
| April | 0.1 °C | 11.9 °C | 62.48 mm |
| May | 7.6 °C | 19.6 °C | 79.5 mm |
| June | 13.7 °C | 24.9 °C | 99.31 mm |
| July | 15.9 °C | 27.2 °C | 103.12 mm |
| August | 14.3 °C | 26.2 °C | 77.72 mm |
| September | 9.3 °C | 22.2 °C | 64.77 mm |
| October | 2.1 °C | 13.8 °C | 60.2 mm |
| November | -5.4 °C | 4.7 °C | 25.91 mm |
| December | -12.4 °C | -3.3 °C | 17.53 mm |
| Annual | 0.6 °C | 11.6 °C | 650.48 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |