Garrison, North Dakota has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -1.2 °C (low) to 11 °C (high). Annual precipitation averages 459.7 Millimeters. Garrison 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 | -17.1 °C | -6.9 °C | 11.94 mm |
| February | -15.4 °C | -4.4 °C | 9.65 mm |
| March | -8.8 °C | 2.4 °C | 17.78 mm |
| April | -1.9 °C | 11.4 °C | 27.94 mm |
| May | 5.1 °C | 18.5 °C | 72.14 mm |
| June | 11.1 °C | 23.3 °C | 95.5 mm |
| July | 13.8 °C | 27.1 °C | 68.07 mm |
| August | 12.4 °C | 27.3 °C | 53.09 mm |
| September | 7.1 °C | 21.6 °C | 42.16 mm |
| October | 0.1 °C | 12.7 °C | 32.51 mm |
| November | -7.2 °C | 3.3 °C | 16 mm |
| December | -13.6 °C | -4.2 °C | 12.95 mm |
| Annual | -1.2 °C | 11 °C | 459.73 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 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 | Normal |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |