Greycliff, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 32.9 °F (low) to 60.3 °F (high). Annual precipitation averages 16.4 Inches. Greycliff 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 Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 16.1 °F | 37.9 °F | 0.59 in. |
| February | 16.7 °F | 40.4 °F | 0.6 in. |
| March | 23.8 °F | 49.8 °F | 0.95 in. |
| April | 31.0 °F | 58.0 °F | 2.12 in. |
| May | 39.6 °F | 67.3 °F | 3.09 in. |
| June | 47.5 °F | 76.5 °F | 2.6 in. |
| July | 53.1 °F | 87.3 °F | 1.36 in. |
| August | 50.9 °F | 86.1 °F | 0.98 in. |
| September | 42.9 °F | 75.3 °F | 1.25 in. |
| October | 32.9 °F | 60.5 °F | 1.49 in. |
| November | 23.6 °F | 46.9 °F | 0.69 in. |
| December | 16.2 °F | 37.2 °F | 0.67 in. |
| Annual | 32.9 °F | 60.3 °F | 16.39 in. |
| 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 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |