Dell, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -2.7 °C (low) to 12 °C (high). Annual precipitation averages 265.2 Millimeters. Dell is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Aug. 11 - Aug. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.8 °C | -1.3 °C | 9.14 mm |
| February | -11.6 °C | 0.3 °C | 9.4 mm |
| March | -7.2 °C | 5.4 °C | 12.19 mm |
| April | -3.2 °C | 10.9 °C | 27.94 mm |
| May | 1 °C | 16.3 °C | 42.67 mm |
| June | 5 °C | 21.4 °C | 52.32 mm |
| July | 8.1 °C | 27.6 °C | 25.4 mm |
| August | 7.2 °C | 27.1 °C | 23.62 mm |
| September | 3.1 °C | 21.3 °C | 19.05 mm |
| October | -2.3 °C | 12.9 °C | 25.15 mm |
| November | -7.7 °C | 4.3 °C | 8.13 mm |
| December | -12.5 °C | -1.7 °C | 10.16 mm |
| Annual | -2.7 °C | 12 °C | 265.17 mm |
| Average First Frost Date | Aug. 11 - Aug. 20 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |