Oslo, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.3 °C (low) to 9.9 °C (high). Annual precipitation averages 592.6 Millimeters. Oslo is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -19.5 °C | -9.7 °C | 15.24 mm |
| February | -17.6 °C | -7 °C | 14.22 mm |
| March | -9.6 °C | 0.2 °C | 21.59 mm |
| April | -1 °C | 10.6 °C | 30.48 mm |
| May | 5.9 °C | 18.8 °C | 86.11 mm |
| June | 12.4 °C | 24.1 °C | 106.93 mm |
| July | 14.4 °C | 26.6 °C | 86.36 mm |
| August | 12.8 °C | 26.3 °C | 75.18 mm |
| September | 7.8 °C | 21.2 °C | 65.53 mm |
| October | 1 °C | 12.2 °C | 48.51 mm |
| November | -7.3 °C | 1.9 °C | 22.35 mm |
| December | -14.8 °C | -6.2 °C | 20.07 mm |
| Annual | -1.3 °C | 9.9 °C | 592.57 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |