Sylvanite, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.4 °C (low) to 13.4 °C (high). Annual precipitation averages 847.6 Millimeters. Sylvanite is located in USDA Plant Hardiness Zone 6a. 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 | -7.7 °C | -0.3 °C | 99.82 mm |
| February | -7.4 °C | 3.1 °C | 64.01 mm |
| March | -4.4 °C | 7.9 °C | 82.04 mm |
| April | -1.6 °C | 13.2 °C | 58.42 mm |
| May | 2.6 °C | 19.3 °C | 69.85 mm |
| June | 6.1 °C | 22.6 °C | 70.61 mm |
| July | 8.3 °C | 28.3 °C | 26.42 mm |
| August | 7.7 °C | 28.5 °C | 24.13 mm |
| September | 3.7 °C | 22.2 °C | 40.89 mm |
| October | -0.6 °C | 12.7 °C | 98.3 mm |
| November | -4.1 °C | 3.8 °C | 107.44 mm |
| December | -7.3 °C | -0.9 °C | 105.66 mm |
| Annual | -0.4 °C | 13.4 °C | 847.59 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 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |