Elliston, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -3.1 °C (low) to 12.2 °C (high). Annual precipitation averages 442 Millimeters. Elliston is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.7 °C | 0.4 °C | 26.92 mm |
| February | -11.1 °C | 1.9 °C | 23.88 mm |
| March | -7.1 °C | 6.6 °C | 28.45 mm |
| April | -3.5 °C | 10.7 °C | 43.69 mm |
| May | 0.8 °C | 15.8 °C | 53.85 mm |
| June | 4.2 °C | 20.6 °C | 77.72 mm |
| July | 6.9 °C | 26.9 °C | 35.31 mm |
| August | 5.8 °C | 26.6 °C | 33.02 mm |
| September | 2.1 °C | 20.5 °C | 34.29 mm |
| October | -3.2 °C | 12.2 °C | 34.29 mm |
| November | -8.1 °C | 4.7 °C | 28.19 mm |
| December | -12 °C | -0.1 °C | 22.35 mm |
| Annual | -3.1 °C | 12.2 °C | 441.96 mm |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |