Ostrander, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.6 °C (low) to 11.9 °C (high). Annual precipitation averages 892.6 Millimeters. Ostrander 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 | -14.4 °C | -5.6 °C | 22.61 mm |
| February | -12.2 °C | -3.1 °C | 24.38 mm |
| March | -5.7 °C | 3.8 °C | 44.2 mm |
| April | 1.1 °C | 12.3 °C | 94.23 mm |
| May | 8 °C | 19.3 °C | 116.84 mm |
| June | 13.9 °C | 24.7 °C | 145.54 mm |
| July | 15.7 °C | 26.6 °C | 108.2 mm |
| August | 14.2 °C | 25.4 °C | 105.41 mm |
| September | 9.7 °C | 21.9 °C | 90.93 mm |
| October | 2.8 °C | 14.2 °C | 67.82 mm |
| November | -3.9 °C | 5.3 °C | 41.66 mm |
| December | -10.4 °C | -2.3 °C | 30.73 mm |
| Annual | 1.6 °C | 11.9 °C | 892.55 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 | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |