Stanley, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.3 °C (low) to 9.9 °C (high). Annual precipitation averages 470.4 Millimeters. Stanley 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 | -18 °C | -7.9 °C | 13.72 mm |
| February | -15.9 °C | -5.5 °C | 12.95 mm |
| March | -9.6 °C | 1.3 °C | 18.03 mm |
| April | -2.6 °C | 10.8 °C | 27.94 mm |
| May | 4 °C | 17.6 °C | 64.01 mm |
| June | 9.9 °C | 22.2 °C | 99.82 mm |
| July | 12.3 °C | 25.8 °C | 74.17 mm |
| August | 11.1 °C | 26.2 °C | 49.78 mm |
| September | 5.7 °C | 20.8 °C | 40.13 mm |
| October | -1 °C | 11.6 °C | 34.54 mm |
| November | -8.4 °C | 1.9 °C | 18.8 mm |
| December | -14.8 °C | -5.5 °C | 16.51 mm |
| Annual | -2.3 °C | 9.9 °C | 470.4 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 3b : -37.2°C to -34.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |