Aitkin, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.9 °C (low) to 10.7 °C (high). Annual precipitation averages 753.4 Millimeters. Aitkin is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -18 °C | -7.1 °C | 21.34 mm |
| February | -16.3 °C | -3.9 °C | 19.05 mm |
| March | -9.1 °C | 3.1 °C | 36.83 mm |
| April | -1.3 °C | 10.9 °C | 61.72 mm |
| May | 5.6 °C | 18.4 °C | 90.93 mm |
| June | 11.4 °C | 23.7 °C | 113.28 mm |
| July | 13.9 °C | 26.2 °C | 113.54 mm |
| August | 12.3 °C | 24.9 °C | 88.65 mm |
| September | 7.7 °C | 20.4 °C | 75.18 mm |
| October | 1.3 °C | 12.4 °C | 69.09 mm |
| November | -5.6 °C | 3.3 °C | 38.35 mm |
| December | -12.9 °C | -4.1 °C | 25.4 mm |
| Annual | -0.9 °C | 10.7 °C | 753.36 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |