Saco, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -1.4 °C (low) to 13.3 °C (high). Annual precipitation averages 328.2 Millimeters. Saco is located in USDA Plant Hardiness Zone 3b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -16.5 °C | -3.9 °C | 8.13 mm |
| February | -14.4 °C | -0.7 °C | 7.87 mm |
| March | -7.8 °C | 6.1 °C | 9.91 mm |
| April | -1.2 °C | 14.7 °C | 26.42 mm |
| May | 4.8 °C | 19.8 °C | 45.72 mm |
| June | 10.1 °C | 24.2 °C | 76.96 mm |
| July | 13.2 °C | 29.4 °C | 40.89 mm |
| August | 11.8 °C | 29.3 °C | 32 mm |
| September | 6.1 °C | 22.9 °C | 31.75 mm |
| October | -0.7 °C | 14.6 °C | 25.91 mm |
| November | -8.2 °C | 5.4 °C | 12.95 mm |
| December | -14.1 °C | -1.8 °C | 9.65 mm |
| Annual | -1.4 °C | 13.3 °C | 328.16 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 3b : -37.2°C to -34.4°C |
| Plant Hardiness Zone - 2012 | Zone 3b : -37.2°C to -34.4°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |