Gardiner, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.4 °C (low) to 14.2 °C (high). Annual precipitation averages 259.1 Millimeters. Gardiner is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.6 °C | 0.7 °C | 12.7 mm |
| February | -9.3 °C | 2.7 °C | 11.18 mm |
| March | -5 °C | 8.1 °C | 16 mm |
| April | -1.2 °C | 13 °C | 19.81 mm |
| May | 3 °C | 18.5 °C | 36.83 mm |
| June | 6.8 °C | 23.8 °C | 37.85 mm |
| July | 10.2 °C | 29.8 °C | 23.62 mm |
| August | 9.3 °C | 29.3 °C | 16.76 mm |
| September | 5.3 °C | 23.6 °C | 20.83 mm |
| October | 0.2 °C | 14.7 °C | 24.89 mm |
| November | -5.3 °C | 5.7 °C | 22.61 mm |
| December | -9.6 °C | 0.1 °C | 16 mm |
| Annual | -0.4 °C | 14.2 °C | 259.08 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |