Carlton, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.6 °C (low) to 15.4 °C (high). Annual precipitation averages 331 Millimeters. Carlton is located in USDA Plant Hardiness Zone 6a. 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 | -7.2 °C | 2 °C | 21.84 mm |
| February | -6.2 °C | 4.6 °C | 24.13 mm |
| March | -3.2 °C | 10.3 °C | 20.07 mm |
| April | -0.2 °C | 15 °C | 29.21 mm |
| May | 3.8 °C | 20.3 °C | 43.43 mm |
| June | 7.4 °C | 24.3 °C | 43.69 mm |
| July | 9.8 °C | 30.8 °C | 18.29 mm |
| August | 8.9 °C | 30.2 °C | 19.81 mm |
| September | 5 °C | 24.1 °C | 21.59 mm |
| October | 0.1 °C | 15.3 °C | 28.7 mm |
| November | -4.2 °C | 6.3 °C | 29.46 mm |
| December | -7.2 °C | 1.2 °C | 30.73 mm |
| Annual | 0.6 °C | 15.4 °C | 330.95 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| 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 |