Janesville, Minnesota has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 1.9 °C (low) to 12.6 °C (high). Annual precipitation averages 874.5 Millimeters. Janesville 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 | -14.6 °C | -5 °C | 22.35 mm |
| February | -12.4 °C | -2.4 °C | 22.86 mm |
| March | -5.3 °C | 4.5 °C | 44.7 mm |
| April | 1.5 °C | 13.2 °C | 78.23 mm |
| May | 8.4 °C | 20.1 °C | 109.98 mm |
| June | 14.6 °C | 25.7 °C | 134.37 mm |
| July | 16.4 °C | 27.4 °C | 117.6 mm |
| August | 15 °C | 26.2 °C | 115.06 mm |
| September | 10.3 °C | 22.8 °C | 96.27 mm |
| October | 3.1 °C | 15.1 °C | 65.02 mm |
| November | -3.9 °C | 5.8 °C | 39.37 mm |
| December | -10.5 °C | -1.9 °C | 28.7 mm |
| Annual | 1.9 °C | 12.6 °C | 874.51 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |